U.S. patent application number 14/970633 was filed with the patent office on 2016-04-14 for golf ball incorporating an innermost hollow portion.
This patent application is currently assigned to Acushnet Company. The applicant listed for this patent is Acushnet Company. Invention is credited to Mark L. Binette, Brian Comeau, Michael J. Sullivan.
Application Number | 20160101324 14/970633 |
Document ID | / |
Family ID | 55654750 |
Filed Date | 2016-04-14 |
United States Patent
Application |
20160101324 |
Kind Code |
A1 |
Sullivan; Michael J. ; et
al. |
April 14, 2016 |
GOLF BALL INCORPORATING AN INNERMOST HOLLOW PORTION
Abstract
Golf ball incorporating: spherical or aspherical innermost
hollow portion; shell layer, one or more outer core layers, and at
least one cover layer. Shell layer has outer surface hardness
greater than inner surface hardness by up to about 7 Shore C to
define first hardness gradient. Outer core layer has a second
hardness gradient. A shell layer surrounding a spherical hollow
portion may have an inner surface with a non-uniform contour
defining a phantom spherical circumference of the innermost
spherical hollow portion at symmetrically spaced locations about
the golf ball's geometric center. In golf balls including a
spherical or aspherical innermost hollow portions, the outer
surface can have non-uniform contour bordering and defining a
contour of a second inner surface of outer core layer. The outer
surface hardness and a second inner surface hardness of second
inner surface differ and alternate symmetrically and
circumferentially about the shell layer inner surface.
Inventors: |
Sullivan; Michael J.; (Old
Lyme, CT) ; Binette; Mark L.; (Mattapoisett, MA)
; Comeau; Brian; (Berkley, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Acushnet Company |
Fairhaven |
MA |
US |
|
|
Assignee: |
Acushnet Company
Fairhaven
MA
|
Family ID: |
55654750 |
Appl. No.: |
14/970633 |
Filed: |
December 16, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14959190 |
Dec 4, 2015 |
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14970633 |
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13736993 |
Jan 9, 2013 |
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14959190 |
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13736997 |
Jan 9, 2013 |
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13736993 |
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13737026 |
Jan 9, 2013 |
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13736997 |
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13737041 |
Jan 9, 2013 |
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13737026 |
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Current U.S.
Class: |
473/375 |
Current CPC
Class: |
A63B 37/0041 20130101;
A63B 37/0077 20130101; A63B 37/0044 20130101; A63B 37/0051
20130101; A63B 37/0092 20130101; A63B 37/0027 20130101; A63B 37/008
20130101; A63B 37/0075 20130101; A63B 37/0043 20130101; A63B
37/0056 20130101; A63B 37/0031 20130101; A63B 37/006 20130101; A63B
37/0064 20130101; A63B 37/0076 20130101 |
International
Class: |
A63B 37/00 20060101
A63B037/00 |
Claims
1. A golf ball comprising: a hollow core comprising: an innermost
spherical hollow portion having a diameter of about 0.15 inches to
about 1.1 inches; surrounded by a shell layer formed from a
thermoplastic composition; and at least one outer core layer formed
from a thermoset composition disposed about the shell layer;
wherein the shell layer has a non-uniform thickness, an inner
surface having an inner surface hardness, and an outer surface
having an outer surface hardness greater than the inner surface
hardness by up to about 7 Shore C to define a first hardness
gradient; and an outer core layer formed about the outer surface
and having a second hardness gradient; and at least one cover layer
disposed about the core.
2. The golf ball of claim 1, wherein the inner surface has a
non-uniform contour that defines a phantom spherical circumference
of the innermost spherical hollow portion at symmetrically spaced
locations about a geometric center of the golf ball.
3. The golf ball of claim 1, wherein the outer surface has a
non-uniform contour that borders and defines a contour of a second
inner surface of the outer core layer, wherein the outer surface
hardness and a second inner surface hardness of the second inner
surface differ.
4. The golf ball of claim 1, wherein the first hardness gradient is
about 1 to 5 Shore C.
5. The golf ball of claim 1, wherein the second hardness gradient
is a negative hardness gradient of about 3 to 25 Shore C.
6. The golf ball of claim 1, wherein the second hardness gradient
is a positive hardness gradient of about 3 to 25 Shore C.
7. The golf ball of claim 1, wherein the cover comprises an inner
cover layer disposed about the outer core layer and comprising an
ionomeric material and having a first hardness; and an outer cover
layer disposed about the inner cover layer and comprising a
polyurea or a polyurethane and having a second hardness less than
the first.
8. A golf ball comprising: a core comprising: an innermost
aspherical hollow portion having a volume V.sub.ahp; surrounded by
a shell layer that is formed from a thermoplastic composition and
has an inner surface comprising a plurality of symmetrically spaced
extensions that border and define a shape of the innermost
aspherical hollow portion; wherein the plurality of extensions and
innermost aspherical hollow portion, combined, form a phantom
sphere having a diameter of from about 0.15 inches to about 1.1
inches; and wherein the plurality of extensions have a combined
total volume E.sub.TV such that V.sub.ahp.gtoreq.E.sub.TV>0.20
(E.sub.TV+V.sub.ahp); and wherein an outer surface of the shell
layer has a non-uniform contour and an outer surface hardness
greater than an inner surface hardness of the inner surface by up
to about 7 Shore C to define a first hardness gradient; and an
outer core layer disposed about the outer surface and having a
second hardness gradient; and at least one cover layer disposed
about the outer core layer.
9. The golf ball of claim 8, wherein the aspherical hollow portion
has a shape that is axially symmetric.
10. The golf ball of claim 9, wherein the aspherical hollow portion
is at least one of non-spherical or irregularly-shaped.
11. The golf ball of claim 8, wherein the plurality of extensions
and innermost aspherical hollow portion, combined, form a spherical
phantom sphere having a diameter of from about 0.30 inches to about
0.90 inches.
12. The golf ball of claim 8, wherein the non-uniform contour
borders and defines a contour of a second inner surface of the
outer core layer, wherein the outer surface hardness and a second
inner surface hardness of the second inner surface differ.
13. The golf ball of claim 8, wherein the first hardness gradient
is about 1 to 5 Shore C.
14. The golf ball of claim 8, wherein the at least one cover layer
comprises an inner cover layer disposed about the outer core layer
and comprising an ionomeric material and having a first hardness;
and an outer cover layer disposed about the inner cover layer and
comprising a polyurea or a polyurethane and having a second
hardness less than the first.
15. The golf ball of claim 8, wherein the innermost aspherical
hollow portion, shell layer and outer core layer, combined, have an
outer diameter of from about 0.75 inches to about 1.62 inches.
16. The golf ball of claim 8, wherein the second hardness gradient
is a negative hardness gradient of about 3 to 25 Shore C.
17. The golf ball of claim 8, wherein the second hardness gradient
is a positive hardness gradient of about 3 to 25 Shore C.
18. The golf ball of claim 8, wherein the outer core layer is
formed from a thermoset composition.
19. The golf ball of claim 8, wherein at least one outer core layer
is formed from a thermoplastic composition.
20. A golf ball comprising: a core comprising: a shell layer that
is formed from a thermoplastic composition and has an inner surface
comprising a plurality of symmetrically spaced extensions that
border and define a shape of an innermost aspherical hollow
portion; wherein the innermost aspherical hollow portion comprise
from about 2% to about 30% of a total volume of the golf ball;
wherein an outer surface of the shell layer has a non-uniform
contour and an outer surface hardness greater than an inner surface
hardness of the inner surface by up to about 7 Shore C to define a
first hardness gradient; and an outer core layer disposed about the
outer surface and having a second hardness gradient; and at least
one cover layer disposed about the core.
21. The golf ball of claim 20, wherein the innermost aspherical
hollow portion has a shape that is axially symmetric.
22. The golf ball of claim 21, wherein the innermost aspherical
hollow portion is at least one of non-spherical or
irregularly-shaped.
23. The golf ball of claim 20, wherein the plurality of extensions
and innermost aspherical hollow portion, combined, form a phantom
sphere having a diameter of from about 0.15 inches to about 1.1
inches.
24. The golf ball of claim 20, wherein the non-uniform contour
borders and defines a contour of a second inner surface of the
outer core layer, wherein the outer surface hardness and a second
inner surface hardness of the second inner surface differ.
25. The golf ball of claim 20, wherein the first hardness gradient
is about 1 to 5 Shore C.
26. The golf ball of claim 20, wherein the at least one cover layer
comprises an inner cover layer disposed about the outer core layer,
and an outer cover layer disposed about the inner cover layer,
wherein the inner cover layer comprises an ionomeric material and
has a first hardness, and the outer cover layer comprises a
polyurea or a polyurethane and has a second hardness less than the
first.
27. The golf ball of claim 20, wherein the innermost aspherical
hollow portion, shell layer and outer core layer, combined, have an
outer diameter of from about 0.75 inches to about 1.62 inches.
28. The golf ball of claim 20, wherein the second hardness gradient
is a negative hardness gradient of about 3 to 25 Shore C.
29. The golf ball of claim 20, wherein the second hardness gradient
is a positive hardness gradient of about 3 to 25 Shore C.
30. The golf ball of claim 20, wherein at least one outer core
layer is formed from a thermoset composition.
31. The golf ball of claim 20, wherein at least one outer core
layer is formed from a thermoplastic composition.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation-in-part of U.S.
patent application Ser. No. 14/959,190, filed on Dec. 4, 2015, and
also a continuation-in-part of U.S. patent application Ser. Nos.
13/736,993, 13/736,997, 13/737,026, and 13/737,041, each filed on
Jan. 9, 2013, the entire disclosures of which are hereby
incorporated herein by reference in their entireties.
FIELD OF THE INVENTION
[0002] This invention relates generally to hollow core golf ball
constructions that target desirable aerodynamic and/or inertial
properties and feel without sacrificing durability.
BACKGROUND OF THE INVENTION
[0003] In recent years, virtually all golf balls are of a solid
construction, typically including a solid core encased by a cover,
both of which can have multiple layers, such as a dual core having
a solid center and an outer core layer, or a multi-layer cover
having an inner and outer cover layer. Golf ball cores are often
formed at least in part from a thermoset rubber composition with
polybutadiene as the base rubber. The cores are usually heated and
crosslinked to create a core having certain pre-determined
characteristics, such as compression or hardness, which result in a
golf ball having the properties for a particular group of players,
whether it be professionals, low-handicap players, or mid-to-high
handicap golfers. From the perspective of a golf ball manufacturer,
it is desirable to have cores exhibiting a wide range of
properties, such as resilience, durability, spin, and "feel,"
because this enables the manufacturer to make and sell golf balls
suited to differing levels of ability.
[0004] Accordingly, golf ball manufacturers continuously experiment
with golf ball constructions and material formulations in order to
target and improve aerodynamic and/or inertial properties and
achieve desired feel without sacrificing durability. One such novel
construction with no past commercial success is a golf ball having
a hollow core--meaning the innermost portion of the core is hollow,
surrounded by a `shell layer` and one or more core and cover
layers. In some hollow core golf ball constructions, an aspherical
hollow space has been created using an insert containing hollow
spaces.
[0005] However, while many prior commercially available golf balls
have been constructed with non-solid centers such as liquid
centers, very few golf balls having hollow centers have ever been
pursued. One reason is that it has been difficult to implement
hollow cores in golf ball constructions and target/improve
aerodynamic and/or inertial properties and achieve desired feel
without sacrificing durability.
[0006] Related co-owned U.S. application Ser. No. 14/959,190, filed
on Dec. 4, 2015 ("'190 application) addresses such adhesion issues.
In particular, the '190 application discloses golf balls wherein an
aspherical hollow space can be created within the core without
using an insert, which prior golf balls had incorporated to create
the aspherical hollow center. One problem encountered with the
prior golf balls incorporating inserts to create an aspherical
hollow space within the core was that poor bonding/adhesion
sometimes occurred between the insert and an adjacent surrounding
layer, resulting in separation of outer layer from the insert when
the golf ball was struck by a club face. In golf balls of the '190
application, a plurality of extensions of the shell layer
advantageously border and define the aspherical shape of the hollow
space within the core. Accordingly, any adhesion problems
previously encountered between the insert and outer layer are
totally eliminated.
[0007] However, there still remains a need for versatile and cost
effective hollow core golf ball constructions that can be
implemented in spherical and aspherical hollow core designs alike
to produce excellent adhesion therein. Such constructions, which
meanwhile target desired playing characteristics and feel with
excellent continuity of hardness distribution from the hollow
interior radially outward, would be particularly desirable. The
golf balls of the invention address and solve all of these
needs.
SUMMARY OF THE INVENTION
[0008] Accordingly, a golf ball of the invention incorporates a
hollow innermost portion that may be spherical or aspherical, and
displays excellent adhesion between layers with desirable
continuity of hardness distribution from the innermost hollow
portion outward toward the golf ball outermost surface.
Advantageously, the core of a golf ball of the invention
incorporates a shell layer having a non-uniform thickness, and a
first hardness gradient that extends from an inner surface of the
shell layer to an outer surface thereof. In particular, the inner
surface has an inner surface hardness, and the outer surface has an
outer surface hardness greater than the inner surface hardness by
up to about 7 Shore C to define the first hardness gradient.
[0009] In one embodiment wherein the innermost hollow portion is
spherical, the inner surface of the shell layer may in particular
have a non-uniform contour that defines a phantom spherical
circumference of the innermost spherical hollow portion at
symmetrically spaced locations about the golf ball's geometric
center. In this embodiment, a plurality of hollow spaces is thereby
created adjacent to the phantom circumference wherein the hollow
spaces and the shell layer alternate symmetrically and
circumferentially about the innermost spherical hollow portion. In
this construction, the area immediately adjacent the innermost
spherical hollow portion therefore comprises alternating hardnesses
of the inner surface and the hollow spaces, thereby providing
excellent continuity of hardness distribution from the innermost
spherical hollow portion, which has a zero hardness, and radially
outward. Advantageously, the hollow spaces have the same zero
hardness as the innermost spherical hollow portion, which creates a
gradual transition from the zero hardness of the very center of the
golf ball to the greater hardnesses of the inner surface of the
shell layer and further outward. Additionally, a second hardness
gradient in the outer core layer continues in creating such
excellent continuity of hardness distribution and adhesion between
golf ball layers in a spherical innermost hollow-type core
construction.
[0010] In embodiments wherein the innermost hollow portion is
spherical or aspherical, the outer surface of the shell layer can
have a non-uniform contour that borders and defines a contour of a
second inner surface of an outer core layer that is disposed about
the outer surface of the shell layer. The outer surface hardness
and a second inner surface hardness of the second inner surface
differ. In this embodiment, the outer surface hardness and second
inner surface hardness may alternate symmetrically and
circumferentially about the inner surface of the shell layer. And
once again, the outer core layer has a second hardness gradient to
further and continue excellent continuity of hardness distribution
and adhesion between golf ball layers in golf ball incorporating
either spherical or aspherical innermost hollow portion-type core
constructions.
[0011] For golf balls incorporating a spherical innermost hollow
portion, embodiments are therefore envisioned wherein both the
inner surface and outer surface of the shell layer simultaneously
have non-uniform contours. In such embodiment, the non-uniform
contours may mirror each other or differ, as long as each is
symmetrically and circumferentially spaced about the golf ball's
geometric center so as to achieve uniform fight and roll when the
golf ball is struck by a club face.
[0012] These and other elements of a golf ball of the invention as
set forth below and elsewhere herein meanwhile target desired
playing characteristics and feel. In a first embodiment, the golf
ball comprises a hollow core comprising an innermost spherical
hollow portion having a diameter of about 0.15 inches to about 1.1
inches. A shell layer, surrounding the innermost spherical hollow
portion, is formed from a thermoplastic composition and has a
non-uniform thickness, with an inner surface having an inner
surface hardness, and an outer surface having an outer surface
hardness greater than the inner surface hardness by up to about 7
Shore C to define a first hardness gradient. The first hardness
gradient in one embodiment may alternatively be about 1 to 5 Shore
C.
[0013] In one embodiment, the inner surface has a non-uniform
contour that defines a phantom spherical circumference of the
innermost spherical hollow portion at symmetrically spaced
locations thereat. In this embodiment, a plurality of hollow spaces
are thereby created adjacent to the phantom circumference which
alternate with the shell layer symmetrically and circumferentially
about the innermost spherical hollow portion such that uniform
flight and roll occur when the finished golf ball is struck by a
club face.
[0014] Meanwhile, at least one outer core layer, formed from a
thermoset composition and having a second hardness gradient, is
formed about the outer surface of the shell layer. In one
embodiment, the second hardness gradient is a negative hardness
gradient of about 3 to 25 Shore C. In another embodiment, the
second hardness gradient is a positive hardness gradient of about 3
to 25 Shore C.
[0015] In one embodiment, the golf ball may further comprise a
thermoplastic intermediate core layer that is disposed between the
shell layer and the outer core layer and comprises a thermoplastic
composition that is different than the thermoplastic composition of
the shell layer.
[0016] Alternatively, the golf ball may comprise a thermoset
intermediate core layer that is disposed between the shell layer
and the outer core layer and comprises a thermoset composition that
is different than the thermoset composition of the outer core
layer; wherein the surface hardness is greater than the inner
surface hardness by about 3 to 25 Shore C. For example, the
thermoset composition of the outer core layer may comprise a
thermoset rubber composition whereas the thermoset intermediate
core layer comprises a different thermoset composition.
[0017] In another embodiment, the outer surface may have a
non-uniform contour that borders and defines a contour of a second
inner surface of an outer core layer that is disposed about the
outer surface of the shell layer. The outer surface hardness and a
second inner surface hardness of the second inner surface differ.
In this embodiment, the outer surface hardness and second inner
surface hardness may alternate symmetrically and circumferentially
about the inner surface of the shell layer.
[0018] Of course, constructions are envisioned wherein the shell
layer includes both of the aforementioned embodiments described
above relating to the contour of the inner surface and the contour
of the outer surface.
[0019] Many suitable patterns and designs are envisioned for the
contour in a shell layer having a non-uniform thickness--for
example, the shell layer may have an inner and/or outer surface
contour that is wave-like.
[0020] At least one cover layer is disposed about the at least one
outer core layer. In one embodiment, the cover comprises an inner
cover layer disposed about the outer core layer and comprising an
ionomeric material and having a first hardness; and an outer cover
layer disposed about the inner cover layer and comprising a
polyurea or a polyurethane and having a second hardness less than
the first.
[0021] In a second embodiment, the shell layer is formed from a
first thermoset rubber composition; and at least one outer core
layer is formed from a second thermoset composition disposed about
the shell layer. The shell layer has an inner surface having an
inner surface hardness and an outer surface having an outer surface
hardness greater than the inner surface hardness by about 3 to 25
Shore C to define a first hardness gradient. And the outer core
layer has a second hardness gradient different from the first
hardness gradient.
[0022] In one embodiment, the second hardness gradient is about 0
Shore C. In another embodiment, the second hardness gradient is a
negative hardness gradient of about 2 to 25 Shore C. In yet another
embodiment, the second hardness gradient is a positive hardness
gradient of about 3 to 10 Shore C.
[0023] The golf ball may further comprise a thermoplastic
intermediate core layer disposed between the shell layer and the
outer core layer; wherein the inner cover layer has a material
hardness greater than about 60 Shore D; and wherein the outer cover
layer has a material hardness of less than about 60 Shore D; and
wherein the surface hardness is greater than the inner surface
hardness by about 10 to 25 Shore C.
[0024] Alternatively, the golf ball may further comprise a
thermoset intermediate core layer disposed between the shell layer
and the outer core layer comprising a third thermoset rubber
composition different from the first and the second; wherein the
surface hardness is greater than the inner surface hardness by
about 10 to 25 Shore C.
[0025] In a third embodiment, the shell layer is formed from a
thermoset rubber composition; and at least one outer core layer is
formed from a thermoplastic composition disposed about the shell
layer. The shell layer has an inner surface having an inner surface
hardness and an outer surface having an outer surface hardness
greater than the inner surface hardness by about 3 to 25 Shore C to
define a first hardness gradient. And the outer core layer has a
second hardness gradient.
[0026] In one embodiment, the second hardness gradient is about 0
Shore C. In another embodiment, the second hardness gradient is a
negative hardness gradient of about 1 to 10 Shore C. In yet another
embodiment, the second hardness gradient is a positive hardness
gradient of about 1 to 10 Shore C.
[0027] The golf ball may further comprise a thermoplastic
intermediate core layer disposed between the shell layer and the
outer core layer comprising a thermoplastic composition that is
different than the thermoplastic composition of the outer core
layer; wherein the inner cover layer has a material hardness
greater than about 60 Shore D; and wherein the outer cover layer
has a material hardness of less than about 60 Shore D; and wherein
the surface hardness is greater than the inner surface hardness by
about 3 to 25 Shore C.
[0028] Alternatively, the golf ball may further comprise a
thermoset intermediate core layer disposed between the shell layer
and the outer core layer comprising a thermoset composition that is
different than the thermoset rubber composition of the shell layer;
wherein the surface hardness is greater than the inner surface
hardness by about 3 to 25 Shore C.
[0029] In a fourth embodiment, the shell layer may be formed from a
first thermoplastic composition; and at least one outer core layer
formed from a second thermoplastic composition disposed about the
shell layer. The shell layer has an inner surface having an inner
surface hardness and an outer surface having an outer surface
hardness greater than the inner surface hardness by up to about 7
Shore C to define a first hardness gradient. And the outer core
layer has a second hardness gradient different from the first
hardness gradient.
[0030] The golf ball may further comprise a thermoplastic
intermediate core layer that is disposed between the shell layer
and the outer core layer and comprises a third thermoplastic
composition different from the first and the second.
[0031] Alternatively, the golf ball may further comprise a
thermoset intermediate core layer that is disposed between the
shell layer and the outer core layer and comprises a thermoset
composition.
[0032] In a fifth embodiment, the shell layer may be formed from a
first thermoset composition; and at least one outer core layer
formed from a second thermoset composition disposed about the shell
layer. The shell layer has an inner surface having an inner surface
hardness and an outer surface has an outer surface hardness greater
than the inner surface hardness by about 10 to 25 Shore C to define
a first hardness gradient; and the outer core layer has a second
hardness gradient different from the first hardness gradient.
[0033] In each of these embodiments, the spherical hollow portion
may alternatively have a diameter of about 0.20 inches to about 1.1
inches, or of about 0.20 inches to about 0.90 inches, or of about
0.25 inches to about 1.1 inches. And the cover may have one or more
layers as defined herein.
[0034] Furthermore, the outer surface hardness may in one
embodiment be greater than about 55 Shore C.
[0035] Moreover, the shell layer may have a coefficient of
restitution less than about 0.700 when measured at an incoming
velocity of 125 ft/s. And a combination of the shell layer and the
outer core layer may have a coefficient of restitution (measured at
an incoming velocity of 125 ft/s) that is higher than the
coefficient of restitution (also measured at an incoming velocity
of 125 ft/s) of the shell layer by 10-50%.
[0036] In one embodiment, the inner cover has a hardness of greater
than about 60 Shore D and the outer cover layer has a hardness of
less than about 60 Shore D. And the golf ball may have a first
volume, and the spherical hollow portion have a second volume that
is about 2% to 30% of the first volume.
[0037] Advantageously, a golf ball of the invention may also be
constructed to target desired playing characteristics and feel yet
create excellent adhesion between layers and continuity of hardness
distribution in aspherical hollow core golf balls.
[0038] In a first embodiment, the golf ball comprises a core, and
one or more cover layers. The core comprises an innermost
aspherical hollow portion, a shell layer, and one or more outer
core layers. The innermost aspherical hollow portion has a volume
V.sub.ahp. The shell layer is formed from a thermoplastic
composition and has an inner surface comprising a plurality of
symmetrically spaced extensions that border and define a shape of
the innermost aspherical hollow portion. The plurality of
extensions and innermost aspherical hollow portion, combined, form
a phantom sphere having a diameter of from about 0.15 inches to
about 1.1 inches. And the plurality of extensions have a combined
total volume E.sub.TV such that V.sub.ahp.gtoreq.E.sub.TV>0.20
(E.sub.TV+V.sub.ahp).
[0039] Meanwhile, the shell layer also has a non-uniform contour
that borders and defines a contour of a second inner surface of an
outer core layer that is disposed about the outer surface of the
shell layer. The outer surface hardness and a second inner surface
hardness of the second inner surface differ. In this embodiment,
the outer surface hardness and second inner surface hardness may
alternate symmetrically and circumferentially about the inner
surface of the shell layer as well as about the golf ball's
geometric center.
[0040] Additionally, the inner surface has an inner surface
hardness and the outer surface has an outer surface hardness
greater than the inner surface hardness by up to about 7 Shore C to
define a first hardness gradient; and the outer core layer has a
second hardness gradient.
[0041] The aspherical hollow portion has a shape that is axially
symmetric. The aspherical hollow portion may be at least one of
non-spherical or irregularly-shaped.
[0042] The plurality of extensions and innermost aspherical hollow
portion, combined, may alternatively form a spherical phantom
sphere having a diameter of from about 0.30 inches to about 0.90
inches.
[0043] In one embodiment, the outer core layer is formed from a
thermoset composition. In another embodiment, the at least one
outer core layer is formed from a thermoplastic composition.
[0044] The first hardness gradient may alternatively be about 1 to
5 Shore C.
[0045] The innermost aspherical hollow portion, shell layer and
outer core layer, combined, may have an outer diameter of from
about 0.75 inches to about 1.62 inches, for example. The second
hardness gradient may be a negative hardness gradient of about 3 to
25 Shore C. Alternatively, the second hardness gradient may be a
positive hardness gradient of about 3 to 25 Shore C.
[0046] That is, the plurality of extensions have a combined volume
E.sub.TV that is equal to or less than volume V.sub.ahp of the
innermost aspherical hollow portion but greater than 20% of the
total volume E.sub.TV+V.sub.ahp of the plurality of extensions and
innermost aspherical hollow portion, combined.
[0047] Herein, the phantom sphere has a volume that is defined by
the maximum radial distance of the innermost aspherical hollow
portion. In golf balls of the invention, the shell layer may have a
maximum thickness, including extensions, of up to about 0.40
inches, as long as the combined volume E.sub.TV of the extensions
is such that V.sub.ahp.gtoreq.E.sub.TV>0.20(E.sub.TV+V.sub.ahp).
In an alternative embodiment, the combined volume E.sub.TV of the
extensions is such that
V.sub.ahp.gtoreq.E.sub.TV>0.30(E.sub.TV+V.sub.ahp).
[0048] And the shell layer thickness at locations not containing
extensions may in some embodiments be at least partially less than
the maximum thickness, with the extensions being sized and shaped
such that their combined volume E.sub.TV satisfy the relationship
V.sub.ahp.gtoreq.E.sub.TV>0.20(E.sub.TV+V.sub.ahp). In other
embodiments, the shell layer thickness at locations not containing
extensions may be at least partially equal to the maximum
thickness. Regardless, the shell layer has a substantially
non-uniform thickness even at locations not containing extensions,
due to the contour of the shell layer outer surface.
[0049] In one embodiment, the at least one cover layer comprises an
inner cover layer disposed about the outer core layer, and an outer
cover layer disposed about the inner cover layer, wherein the inner
cover layer comprises an ionomeric material and has a first
hardness and the outer cover layer comprises a polyurea or a
polyurethane and has a second hardness less than the first.
[0050] In a second embodiment, the shell layer is formed from a
first thermoset rubber composition; and at least one outer core
layer is formed from a second thermoset composition disposed about
the shell layer. The shell layer has an inner surface having an
inner surface hardness and an outer surface having an outer surface
hardness greater than the inner surface hardness by about 3 to 25
Shore C to define a first hardness gradient. And the outer core
layer has a second hardness gradient different from the first
hardness gradient.
[0051] In one embodiment, the second hardness gradient is about 0
Shore C. In another embodiment, the second hardness gradient is a
negative hardness gradient of about 2 to 25 Shore C. In yet another
embodiment, the second hardness gradient is a positive hardness
gradient of about 3 to 10 Shore C.
[0052] The golf ball may further comprise a thermoplastic
intermediate core layer disposed between the shell layer and the
outer core layer; wherein the inner cover layer has a material
hardness greater than about 60 Shore D; and wherein the outer cover
layer has a material hardness of less than about 60 Shore D; and
wherein the surface hardness is greater than the inner surface
hardness by about 10 to 25 Shore C.
[0053] Alternatively, the golf ball may further comprise a
thermoset intermediate core layer disposed between the shell layer
and the outer core layer comprising a third thermoset rubber
composition different from the first and the second; wherein the
surface hardness is greater than the inner surface hardness by
about 10 to 25 Shore C.
[0054] In a third embodiment, the shell layer is formed from a
thermoset rubber composition; and at least one outer core layer is
formed from a thermoplastic composition disposed about the shell
layer. The shell layer has an inner surface having an inner surface
hardness and an outer surface having an outer surface hardness
greater than the inner surface hardness by about 3 to 25 Shore C to
define a first hardness gradient. And the outer core layer has a
second hardness gradient.
[0055] In one embodiment, the second hardness gradient is about 0
Shore C. In another embodiment, the second hardness gradient is a
negative hardness gradient of about 1 to 10 Shore C. In yet another
embodiment, the second hardness gradient is a positive hardness
gradient of about 1 to 10 Shore C.
[0056] The golf ball may further comprise a thermoplastic
intermediate core layer disposed between the shell layer and the
outer core layer comprising a thermoplastic composition that is
different than the thermoplastic composition of the outer core
layer; wherein the inner cover layer has a material hardness
greater than about 60 Shore D; and wherein the outer cover layer
has a material hardness of less than about 60 Shore D; and wherein
the surface hardness is greater than the inner surface hardness by
about 3 to 25 Shore C.
[0057] Alternatively, the golf ball may further comprise a
thermoset intermediate core layer disposed between the shell layer
and the outer core layer comprising a thermoset composition that is
different than the thermoset rubber composition of the shell layer;
wherein the surface hardness is greater than the inner surface
hardness by about 3 to 25 Shore C.
[0058] In a fourth embodiment, the shell layer may be formed from a
first thermoplastic composition; and at least one outer core layer
formed from a second thermoplastic composition disposed about the
shell layer. The shell layer has an inner surface having an inner
surface hardness and an outer surface having an outer surface
hardness greater than the inner surface hardness by up to about 7
Shore C to define a first hardness gradient. And the outer core
layer has a second hardness gradient different from the first
hardness gradient.
[0059] The golf ball may further comprise a thermoplastic
intermediate core layer that is disposed between the shell layer
and the outer core layer and comprises a third thermoplastic
composition different from the first and the second.
[0060] Alternatively, the golf ball may further comprise a
thermoset intermediate core layer that is disposed between the
shell layer and the outer core layer and comprises a thermoset
composition.
[0061] In a fifth embodiment, the shell layer may be formed from a
first thermoset composition; and at least one outer core layer
formed from a second thermoset composition disposed about the shell
layer. The shell layer has an inner surface having an inner surface
hardness and an outer surface has an outer surface hardness greater
than the inner surface hardness by about 10 to 25 Shore C to define
a first hardness gradient; and the outer core layer has a second
hardness gradient different from the first hardness gradient.
[0062] In each of these embodiments, the spherical hollow portion
may alternatively have a diameter of about 0.20 inches to about 1.1
inches, or of about 0.20 inches to about 0.90 inches, or of about
0.25 inches to about 1.1 inches. And the cover may have one or more
layers as defined herein.
[0063] Furthermore, the outer surface hardness may in one
embodiment be greater than about 55 Shore C.
[0064] Moreover, the shell layer may have a coefficient of
restitution less than about 0.700 when measured at an incoming
velocity of 125 ft/s. And a combination of the shell layer and the
outer core layer may have a coefficient of restitution (measured at
an incoming velocity of 125 ft/s) that is higher than the
coefficient of restitution (also measured at an incoming velocity
of 125 ft/s) of the shell layer by 10-50%.
[0065] A golf ball of the invention may be alternatively
constructed to target desired playing characteristics and feel yet
create excellent adhesion between layers and continuity of hardness
distribution in aspherical hollow center golf balls.
[0066] In a different embodiment of a golf ball incorporating an
aspherical innermost hollow portion, the golf ball comprises a core
and one or more cover layers. The core comprises a shell layer that
is formed from a thermoplastic composition and has an inner surface
comprising a plurality of symmetrically spaced extensions that
border and define a shape of an innermost aspherical hollow
portion. The innermost aspherical hollow portion comprises from
about 2% to about 30% of a total volume of the golf ball. The shell
layer also has a non-uniform contour that borders and defines a
contour of a second inner surface of an outer core layer that is
disposed about the outer surface of the shell layer. The outer
surface hardness and a second inner surface hardness of the second
inner surface differ. In this embodiment, the outer surface
hardness and second inner surface hardness may alternate
symmetrically and circumferentially about the inner surface of the
shell layer.
[0067] Additionally, the inner surface has an inner surface
hardness and the outer surface has an outer surface hardness
greater than the inner surface hardness by up to about 7 Shore C to
define a first hardness gradient; and the outer core layer has a
second hardness gradient.
[0068] The innermost aspherical hollow portion has a shape that is
axially symmetric.
[0069] The innermost aspherical hollow portion may be at least one
of non-spherical or irregularly-shaped.
[0070] The plurality of extensions and innermost aspherical hollow
portion, combined, form a phantom sphere having a diameter of from
about 0.15 inches to about 1.1 inches.
[0071] In one embodiment, the first hardness gradient may be about
1 to 5 Shore C.
[0072] The innermost aspherical hollow portion, shell layer and
outer core layer, combined, have an outer diameter of from about
0.75 inches to about 1.62 inches.
[0073] The second hardness gradient may have a negative hardness
gradient of about 3 to 25 Shore C. Alternatively, the second
hardness gradient may be a positive hardness gradient of about 3 to
25 Shore C.
[0074] In one embodiment, the at least one outer core layer is
formed from a thermoset composition. In another embodiment, the at
least one outer core layer is formed from a thermoplastic
composition.
[0075] In one embodiment, the at least one cover layer comprises an
inner cover layer disposed about the outer core layer, and an outer
cover layer disposed about the inner cover layer, wherein the inner
cover layer comprises an ionomeric material and has a first
hardness, and the outer cover layer comprises a polyurea or a
polyurethane and has a second hardness less than the first.
[0076] In a second embodiment, the shell layer is formed from a
first thermoset rubber composition; and at least one outer core
layer is formed from a second thermoset composition disposed about
the shell layer. The shell layer has an inner surface having an
inner surface hardness and an outer surface having an outer surface
hardness greater than the inner surface hardness by about 3 to 25
Shore C to define a first hardness gradient. And the outer core
layer has a second hardness gradient different from the first
hardness gradient.
[0077] In one embodiment, the second hardness gradient is about 0
Shore C. In another embodiment, the second hardness gradient is a
negative hardness gradient of about 2 to 25 Shore C. In yet another
embodiment, the second hardness gradient is a positive hardness
gradient of about 3 to 10 Shore C.
[0078] The golf ball may further comprise a thermoplastic
intermediate core layer disposed between the shell layer and the
outer core layer; wherein the inner cover layer has a material
hardness greater than about 60 Shore D; and wherein the outer cover
layer has a material hardness of less than about 60 Shore D; and
wherein the surface hardness is greater than the inner surface
hardness by about 10 to 25 Shore C.
[0079] Alternatively, the golf ball may further comprise a
thermoset intermediate core layer disposed between the shell layer
and the outer core layer comprising a third thermoset rubber
composition different from the first and the second; wherein the
surface hardness is greater than the inner surface hardness by
about 10 to 25 Shore C.
[0080] In a third embodiment, the shell layer is formed from a
thermoset rubber composition; and at least one outer core layer is
formed from a thermoplastic composition disposed about the shell
layer. The shell layer has an inner surface having an inner surface
hardness and an outer surface having an outer surface hardness
greater than the inner surface hardness by about 3 to 25 Shore C to
define a first hardness gradient. And the outer core layer has a
second hardness gradient.
[0081] In one embodiment, the second hardness gradient is about 0
Shore C. In another embodiment, the second hardness gradient is a
negative hardness gradient of about 1 to 10 Shore C. In yet another
embodiment, the second hardness gradient is a positive hardness
gradient of about 1 to 10 Shore C.
[0082] The golf ball may further comprise a thermoplastic
intermediate core layer disposed between the shell layer and the
outer core layer comprising a thermoplastic composition that is
different than the thermoplastic composition of the outer core
layer; wherein the inner cover layer has a material hardness
greater than about 60 Shore D; and wherein the outer cover layer
has a material hardness of less than about 60 Shore D; and wherein
the surface hardness is greater than the inner surface hardness by
about 3 to 25 Shore C.
[0083] Alternatively, the golf ball may further comprise a
thermoset intermediate core layer disposed between the shell layer
and the outer core layer comprising a thermoset composition that is
different than the thermoset rubber composition of the shell layer;
wherein the surface hardness is greater than the inner surface
hardness by about 3 to 25 Shore C.
[0084] In a fourth embodiment, the shell layer may be formed from a
first thermoplastic composition; and at least one outer core layer
formed from a second thermoplastic composition disposed about the
shell layer. The shell layer has an inner surface having an inner
surface hardness and an outer surface having an outer surface
hardness greater than the inner surface hardness by up to about 7
Shore C to define a first hardness gradient. And the outer core
layer has a second hardness gradient different from the first
hardness gradient.
[0085] The golf ball may further comprise a thermoplastic
intermediate core layer that is disposed between the shell layer
and the outer core layer and comprises a third thermoplastic
composition different from the first and the second.
[0086] Alternatively, the golf ball may further comprise a
thermoset intermediate core layer that is disposed between the
shell layer and the outer core layer and comprises a thermoset
composition.
[0087] In a fifth embodiment, the shell layer may be formed from a
first thermoset composition; and at least one outer core layer
formed from a second thermoset composition disposed about the shell
layer. The shell layer has an inner surface having an inner surface
hardness and an outer surface has an outer surface hardness greater
than the inner surface hardness by about 10 to 25 Shore C to define
a first hardness gradient; and the outer core layer has a second
hardness gradient different from the first hardness gradient.
[0088] In each of these embodiments, the spherical hollow portion
may alternatively have a diameter of about 0.20 inches to about 1.1
inches, or of about 0.20 inches to about 0.90 inches, or of about
0.25 inches to about 1.1 inches. And the cover may have one or more
layers as defined herein.
[0089] Furthermore, the outer surface hardness may in one
embodiment be greater than about 55 Shore C. Moreover, the shell
layer may have a coefficient of restitution less than about 0.700
when measured at an incoming velocity of 125 ft/s. And a
combination of the shell layer and the outer core layer may have a
coefficient of restitution (measured at an incoming velocity of 125
ft/s) that is higher than the coefficient of restitution (also
measured at an incoming velocity of 125 ft/s) of the shell layer by
10-50%.
BRIEF DESCRIPTION OF THE DRAWINGS
[0090] The accompanying drawings form a part of the specification
and are to be read in conjunction therewith. The illustrated
embodiments, however, are merely examples and are not intended to
be limiting. Like reference numerals and designations in the
various drawings indicate like elements.
[0091] FIG. 1 is a golf ball incorporating a shell layer having a
non-uniform thickness according to one embodiment of the
invention;
[0092] FIG. 2 is a golf ball of the invention incorporating a shell
layer having a non-uniform thickness according to another
embodiment of the invention; and
[0093] FIG. 3 is a golf ball of the invention incorporating a shell
layer having a non-uniform thickness according to yet another
embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0094] Golf balls of the present invention may include multi-layer
golf balls, such as one having a core and a cover surrounding the
core, but are preferably formed from a core having a hollow core
and at least one outer core layer, an inner cover layer, and an
outer cover layer. Any of the core or cover layers may include more
than one layer. The cover layer of the golf ball may be a single
layer or formed of a plurality of layers, such as an inner cover
layer and an outer cover layer. The hollow core comprises an
innermost hollow portion that may be spherical in some embodiments,
or aspherical in other embodiments.
[0095] Advantageously, a golf ball of the invention incorporates a
shell layer having a non-uniform thickness, with an inner surface
of the shell layer has an inner surface hardness, and an outer
surface has an outer surface hardness greater than the inner
surface hardness by up to about 7 Shore C to define a first
hardness gradient. In a first embodiment, incorporating a spherical
innermost hollow portion, the inner surface has a non-uniform
contour that defines a phantom spherical circumference of the
innermost spherical hollow portion at symmetrically spaced
locations thereat. In this embodiment, a plurality of hollow spaces
is thereby created adjacent to the phantom circumference wherein
the hollow spaces and the shell layer alternate symmetrically and
circumferentially about the innermost spherical hollow portion.
[0096] In second embodiment, the golf ball may incorporate a
spherical or aspherical innermost hollow portion, with the outer
surface of the shell layer having a non-uniform contour that
borders and defines a contour of a second inner surface of an outer
core layer that is disposed about the outer surface of the shell
layer. The outer surface hardness and a second inner surface
hardness of the second inner surface differ. In this embodiment,
the outer surface hardness and second inner surface hardness
alternate symmetrically and circumferentially about the inner
surface of the shell layer.
[0097] Constructions are also envisioned wherein the shell layer
incorporates an innermost spherical hollow portion and both the
first and second shell layer embodiments.
[0098] Meanwhile, the outer core layer has a second hardness
gradient.
[0099] Many different patterns/designs are envisioned as being
suitable for forming shell layer surface contours that can be
symmetrically circumferentially disposed about the innermost hollow
portion so as to ensure uniform golf ball flight and roll.
[0100] The first embodiment arrangement permits multiple hardnesses
to occur immediately surrounding the innermost hollow portion,
thereby creating excellent continuity of hardness distribution
within the hollow center golf ball while meanwhile providing
excellent adhesion between the shell layer and surrounding outer
core layer in a hollow core golf ball construction. Specifically,
the inner surface hardness and a zero hardness of the hollow spaces
alternate circumferentially about a zero hardness innermost
spherical hollow center.
[0101] And the second embodiment golf ball construction permits
multiple hardnesses to occur about the interface between the outer
surface of the shell layer and the inner surface of the outer core
layer and circumferentially about the innermost hollow portion. For
additional examples and details suitable for a golf ball of the
invention, see for example, related applications U.S. patent
application Ser. No. 14/959,190, filed on Dec. 4, 2015, and also a
continuation-in-part of U.S. patent application Ser. Nos.
13/736,993, 13/736,997, 13/737,026, and 13/737,041, each filed on
Jan. 9, 2013, and incorporated herein by reference in their
entireties, including all figures thereof.
[0102] FIGS. 1-3 highlight some of the features of golf balls of
the invention and should not be construed as limiting the scope of
the invention. FIG. 1 illustrates one possible golf ball
construction incorporating a spherical innermost hollow portion.
Referring to FIG. 1, golf ball 2 includes core 3, which is
comprised of innermost spherical hollow portion 4, surrounding
shell layer 6, and outer core layer 8, formed about shell layer 6.
Shell layer 6 is has a non-uniform thickness that is created by a
non-uniform contour in inner surface 10 that defines a phantom
spherical circumference 11 of innermost spherical hollow portion 4
at symmetrically spaced locations 12. In this embodiment, a
plurality of hollow spaces 14 are thereby created adjacent to the
phantom spherical circumference 11, with hollow spaces 14
alternating with shell layer 6 symmetrically and circumferentially
about innermost spherical hollow portion 4.
[0103] Inner surface 10 has an inner surface hardness, and an outer
surface 16 of shell layer 6 has an outer surface hardness that is
greater than the inner surface hardness to define a first hardness
gradient of from about 1 to 7 Shore C. Meanwhile, outer core layer
8 has a second inner surface 18 having a second inner surface
hardness, and a second outer surface 20 having a second outer
surface hardness that is different than the second inner surface
hardness to define a second hardness gradient.
[0104] Inner cover layer 22 is disposed about second outer surface
20 of outer core layer 8 and comprises an ionomeric material and
has a first hardness that is greater than a second hardness of
outer cover layer 24 that is disposed about inner cover layer 22
and comprises a polyurea or a polyurethane.
[0105] Alternating hardnesses can therefore be created
symmetrically about and adjacent to the innermost spherical hollow
portion of the core, resulting in unique playing characteristics,
excellent adhesion between layers and excellent continuity of
hardness distribution from the innermost hollow portion and
radially outward.
[0106] Referring to FIG. 2, golf ball 26 includes core 27 which is
comprised of innermost spherical hollow portion 28, surrounding
shell layer 30, and outer core layer 32, formed about shell layer
30. Shell layer 30 has an inner surface 34, having an inner surface
hardness, and an outer surface 36, having an outer surface hardness
that is greater than the inner surface hardness by about 1-7 Shore
C. Shell layer 30 has a non-uniform thickness that is created by a
non-uniform contour of outer surface 36 that borders and defines a
contour of a second inner surface 38 of outer core layer 32. The
outer surface hardness and a second inner surface hardness of the
second inner surface differ and alternate symmetrically and
circumferentially about the inner surface of shell layer 30.
[0107] Meanwhile, a second outer surface 40 of outer core layer 32
has a second outer surface hardness that is different than the
second inner surface hardness to define a second hardness
gradient.
[0108] Inner cover layer 42 is disposed about second outer surface
40 and comprises an ionomeric material and has a first hardness
that is greater than a second hardness of outer cover layer 44,
which is disposed about inner cover layer 42 and comprises a
polyurea or a polyurethane.
[0109] Alternating hardnesses can therefore be created
symmetrically at the interface between the shell layer and outer
core layer to produce unique playing characteristics with excellent
adhesion between layers and also excellent continuity of hardness
distribution from innermost hollow portion and radially
outward.
[0110] Referring to FIG. 3, golf ball 45 includes core 46 that is
comprised of innermost aspherical hollow portion 47, shell layer
48, and outer core layer 49. Shell layer 48 has an inner surface 50
and a plurality of symmetrically spaced extensions 52 that border
and define the shape of innermost aspherical hollow portion 47.
Inner surface 50 has an inner surface hardness, and outer surface
54 of shell layer 48 has an outer surface hardness that is greater
than the inner surface hardness to define a first hardness gradient
of from about 1 to 7 Shore C. Meanwhile, outer surface 54 has a
non-uniform contour that borders and defines a contour of a second
inner surface 56 of outer core layer 49. The outer surface hardness
and a second inner surface hardness of second inner surface 56
differ and alternate symmetrically and circumferentially about the
inner surface.
[0111] Meanwhile, a second outer surface 58 of outer core layer 49
has a second outer surface hardness that is different than the
second inner surface hardness to define a second hardness
gradient.
[0112] Inner cover layer 60 is disposed about second outer surface
58 and comprises an ionomeric material and has a first hardness
that is greater than a second hardness of outer cover layer 62,
which is disposed about inner cover layer 60 and comprises a
polyurea or a polyurethane.
[0113] Alternating hardnesses can therefore be created
symmetrically at the interface between the shell layer and outer
core layer, to achieve unique playing characteristics with
excellent adhesion between layers and also excellent continuity of
hardness distribution from innermost hollow portion and radially
outward.
[0114] Examples of particular embodiments of a golf ball of the
invention, incorporating a shell layer having a non-uniform
thickness as defined herein, may be as follows. In one embodiment,
the hollow core of a golf ball of the invention includes a
thermoset shell layer containing or encasing an innermost spherical
hollow portion. In one embodiment, the thermoset shell layer is
surrounded by at least two outer core layers, where one outer core
layer is formed from a thermoset material, and an intermediate core
layer, disposed between the shell layer and the outer core layer,
is formed from a thermoplastic material. In another embodiment, the
thermoset shell layer is surrounded by at least two outer core
layers, where one outer core layer is formed from a thermoset
material, and an intermediate core layer, disposed between the
shell layer and the outer core layer, is formed from a thermoset
material. In yet another embodiment, the thermoset shell layer is
surrounded by at least two outer core layers, where one outer core
layer is formed from a thermoplastic material, and an intermediate
core layer, disposed between the shell layer and the outer core
layer, is formed from a thermoplastic material. In still another
embodiment, the thermoset shell layer is surrounded by at least two
outer core layers, where one outer core layer is formed from a
thermoplastic material, and an intermediate core layer, disposed
between the shell layer and the outer core layer, is formed from a
thermoset material.
[0115] Alternatively, the shell layer may comprise a thermoplastic
material. For example, in one embodiment, the hollow core includes
a thermoplastic shell layer containing or encasing the innermost
spherical hollow portion. In one embodiment, the thermoplastic
shell layer is surrounded by at least two outer core layers, where
one outer core layer is formed from a thermoset material, and an
intermediate core layer, disposed between the shell layer and the
outer core layer, is formed from a thermoplastic material. In
another embodiment, the thermoplastic shell layer is surrounded by
at least two outer core layers, where one outer core layer is
formed from a thermoset material, and an intermediate core layer,
disposed between the shell layer and the outer core layer, is also
formed from a thermoset material. In yet another embodiment, the
thermoplastic shell layer is surrounded by at least two outer core
layers, where one outer core layer is formed from a thermoplastic
material, and an intermediate core layer, disposed between the
shell layer and the outer core layer, is formed from a
thermoplastic material. In still another embodiment, the
thermoplastic shell layer is surrounded by at least two outer core
layers, where one outer core layer is formed from a thermoplastic
material, and an intermediate core layer, disposed between the
shell layer and the outer core layer, is formed from a thermoset
material.
[0116] In one preferred embodiment, the golf ball includes a hollow
core formed from a thermoset rubber shell layer encasing an
innermost spherical hollow portion. In this embodiment, a single
outer core layer is formed around the shell layer to create the
hollow golf ball core. The outer core layer is also formed from a
thermoset material, which may be the same rubber composition as the
shell layer but is preferably a different thermoset rubber
composition. A single cover layer or multiple cover layers are
formed over the hollow core. Preferably, an inner cover layer and
an outer cover layer are formed over the outer core layer. In one
embodiment, the inner cover includes an ionomeric material and the
outer cover layer includes a polyurea or, preferably, a
polyurethane. The outer cover layer is typically softer than the
inner cover layer, such as where the inner cover has a hardness of
greater than about 60 Shore D and the outer cover layer has a
hardness of less than about 60 Shore D.
[0117] In the above embodiment, the innermost spherical hollow
portion preferably has a diameter of about 0.51 to 1.1 inches. The
surface hardness of the shell layer may be greater than the inner
surface hardness by about 3 to 25 Shore C to define the first
hardness gradient. In a preferred embodiment, the thermoset outer
core layer has a hardness gradient that is different from the
hardness gradient of the thermoset shell layer. Most preferably,
the shell layer has a surface hardness greater than about 55 Shore
C.
[0118] The thermoset shell layer has a coefficient of restitution
(COR) less than about 0.750 when measured at an incoming velocity
of 125 ft/s. Preferably, the COR is less than about 0.700, more
preferably about 0.500 to 0.700, and most preferably about 0.600 to
0.700. The overall hollow core (the combination of the thermoset
shell layer and the thermoset outer core layer) has a COR, measured
at an incoming velocity of 125 ft/s, higher than the COR of the
inner core shell layer by greater than about 5%, more preferably
about 10 to 50%, and most preferably about 15 to 30%.
[0119] In an alternative embodiment, the hardness gradient of the
thermoset outer core layer has a `zero hardness gradient`. The zero
hardness gradient is typically about 0 Shore C (defined herein as
.+-.2 Shore C). The hardness gradient of the thermoset outer core
layer may also have a `negative hardness gradient`, preferably
about 3 to 25 Shore C, more preferably about 5 to 20 Shore C, and
most preferably about 8 to 15 Shore C. The hardness gradient of the
thermoset outer core layer may also have a `positive hardness
gradient`, preferably about 3 to 25 Shore C, more preferably about
5 to 20 Shore C, and most preferably about 8 to 15 Shore C.
[0120] The golf ball has a first volume and the hollow center has a
second volume. The volume of the hollow center is about 2% to 30%
of the golf ball volume, more preferably about 5% to 25% of the
golf ball volume, and most preferably about 10% to 20% of the golf
ball volume.
[0121] Examples of suitable hardness profiles for cores in golf
balls of the invention may be found in related U.S. patent
application Ser. Nos. 13/736,993, 13/736,997, 13/737,026, and
13/737,041, each filed on Jan. 9, 201, and any accompanying FIGS.
1a and 1b thereof, all incorporated by reference herein as stated
further above.
[0122] Golf balls of the invention may also include an aspherical
hollow volume in the center of the golf ball, formed by a shell
layer that meanwhile has a non-uniform contour in the shell layer
outer surface. In such a golf ball of the invention, the shell
layer has a plurality of hollow spaces therein that extend from an
inner surface to an outer surface of the shell layer, and meanwhile
also has a plurality of extensions located on an inner surface that
border and define the shape of the aspherical hollow volume rather
than a separate insert having hollow spaces that form the
aspherical hollow volume. The plurality of extensions and innermost
hollow portion, combined, form a phantom sphere having an
aspherical hollow volume within. Manufacturing costs are meanwhile
also reduced since an aspherical hollow core is constructed such
that the aspherical hollow volume and shell layer are unitary.
[0123] Accordingly, in one embodiment of a golf ball of the
invention, the core comprises: an innermost aspherical hollow
portion having a volume V.sub.ahp; a shell layer that is formed
from a thermoplastic or thermoset composition and has an inner
surface comprising a plurality of symmetrically spaced extensions
that border and define the shape of the innermost aspherical hollow
portion; and at least one outer core layer formed from a thermoset
or thermoplastic composition disposed about the shell layer. The
plurality of extensions and innermost aspherical hollow portion,
combined, form a phantom sphere having a diameter of from about
0.10 inches to about 1.1 inches; and the plurality of extensions
have a combined total volume E.sub.TV such that
V.sub.ahp.gtoreq.E.sub.TV>0.20(E.sub.TV+V.sub.ahp). As defined
above, the plurality of extensions have a combined volume E.sub.TV
that is equal to or less than volume V.sub.ahp of the innermost
aspherical hollow portion but greater than 20% of the total volume
E.sub.TV+V.sub.ahp of the plurality of extensions and innermost
aspherical hollow portion, combined.
[0124] In alternative embodiments, the combined volume E.sub.TV of
the extensions may be such that
V.sub.ahp.gtoreq.E.sub.TV>0.25(E.sub.TV+V.sub.ahp), or
V.sub.ahp.gtoreq.E.sub.TV>0.30(E.sub.TV+V.sub.ahp), or
V.sub.ahp.gtoreq.E.sub.TV>0.35(E.sub.TV+V.sub.ahp), or
V.sub.ahp.gtoreq.E.sub.TV>0.40(E.sub.TV+V.sub.ahp), or
V.sub.ahp.gtoreq.E.sub.TV>0.45(E.sub.TV+V.sub.ahp). In still
other embodiments,
V.sub.ahp.gtoreq.E.sub.TV>.about.0.20(E.sub.TV+V.sub.ahp),
V.sub.ahp.gtoreq.E.sub.TV>.about.0.25(E.sub.TV+V.sub.ahp), or
V.sub.ahp.gtoreq.E.sub.TV>618 0.30(E.sub.TV+V.sub.ahp), or
V.sub.ahp.gtoreq.E.sub.TV>.about.0.35(E.sub.TV+V.sub.ahp), or
V.sub.ahp.gtoreq.E.sub.TV>.about.0.40(E.sub.TV+V.sub.ahp), or
V.sub.ahp.gtoreq.E.sub.TV>.about.0.45(E.sub.TV+V.sub.ahp).
[0125] The plurality of extensions and innermost aspherical hollow
portion, combined, form a phantom sphere having a volume that is
defined by the maximum radial distance of the innermost aspherical
hollow portion. The diameter of the phantom sphere may
alternatively be from about 0.20 inches to about 1.1 inches, or
from about 0.20 inches to about 0.90 inches, or from about 0.25
inches to about 0.75 inches, or from about 0.30 inches to about
0.50 inches, or from about 0.20 inches to about 1.0 inches, or from
about 0.25 inches to about 0.90 inches, or from about 0.30 inches
to about 0.90 inches. In one embodiment, the plurality of
extensions and innermost aspherical hollow portion, combined, has a
diameter of greater than 0.5 inches, or greater than about 1.0
inches.
[0126] Meanwhile, the shell layer has an outer surface with a
non-uniform contour. Additionally, the inner surface has an inner
surface hardness and the outer surface has an outer surface
hardness greater than the inner surface hardness by up to about 7
Shore C to define a first hardness gradient; and the outer core
layer has a second hardness gradient.
[0127] The shell layer may have a maximum thickness, including
extensions, of up to about 0.40 inches, or up to about 0.375
inches, or up to about 0.30 inches, or up to about 0.275 inches, or
up to about 0.200 inches, or up to about 0.175 inches. In one
embodiment, wherein the shell layer is relatively thick, the shell
layer maximum thickness is from about 0.125 inches to about 0.375
inches, or from about 0.2 inches to about 0.3125 inches, or from
about 0.25 inches to about 0.3 inches, or from about 0.26 inches to
about 0.275 inches.
[0128] In some embodiments, the shell layer may have a thickness at
locations not containing extensions of greater than about 0.01
inches but less than the maximum thickness. When the shell layer is
desired to be relatively thin at locations not containing
extensions, that thickness may be from about 0.01 inches to about
0.1 inches, or from about 0.02 inches to about 0.075 inches, or
from about 0.025 inches to about 0.04 inches, or from about 0.03
inches to about 0.035 inches.
[0129] When the shell layer is relatively thin and formed from a
thermoplastic material, the thermoplastic material is preferably
selected to be somewhat heat resistant (or blended with a heat
resistant thermoplastic material) to avoid melting of the layer by
subsequent molding of additional core and/or cover layers.
[0130] With the dimensions of the hollow interior in mind, the
hollow cores (innermost aspherical hollow portion, shell layer and
outer core layer(s)) of the invention may have an outer diameter of
about 0.75 inches to about 1.62 inches, or about 0.75 inches to
about 1.58 inches, or about 1.0 inches to about 1.57 inches, or
about 1.3 inches to about 1.56 inches, or about 1.4 inches to about
1.55 inches. The shell layer may have an outer diameter of about
0.75 inches, 1.0 inches, 1.20 inches, or 1.30 inches, with one
outer diameter being 0.75 inches, or 1.0 inches.
[0131] In an alternative embodiment, the outer core layer should
have an outer diameter (the entire hollow core, shell layer plus
outer core layer) of about 1.30 inches to about 1.62 inches, or 1.4
inches to about 1.6 inches, or about 1.5 inches to about 1.59
inches. In some embodiments, the outer core layer has an outer
diameter of about 1.51 inches, 1.53 inches, or 1.550 inches.
[0132] The inner and outer cover layers may for example have a
thickness of about 0.010 to 0.080 inches, or about 0.015 to 0.060
inches, or about 0.020 to 0.040 inches. Alternatively, the inner
and outer cover layers have a thickness of about 0.015 inches to
about 0.055 inches, or about 0.02 inches to about 0.04 inches, or
about 0.025 inches to about 0.035 inches. The inner cover layer, if
present, may have a hardness of about 60 Shore D or greater, or
about 65 Shore D or greater, or about 70 Shore D or greater. The
inner cover layer may harder than the outer cover layer although
embodiments are envisioned wherein the outer cover layer is harder
than the inner cover layer. The outer cover layer may have a
hardness of about 60 Shore D or less, or about 55 Shore D or less,
or about 50 Shore D or less.
[0133] FIGS. 1-6 of related U.S. patent application Ser. No.
14/959,190, filed on Dec. 4, 2015 (incorporated by reference herein
in its entirety above) provide examples of some suitable
constructions for shell layers forming aspherical innermost hollow
portions, etc.
[0134] In golf balls of the present invention, any of the core,
cover, or intermediate layer may include more than one layer.
[0135] In one embodiment, the hollow core is formed of a thermoset
shell layer that borders and defines the innermost aspherical
hollow portion. In another embodiment, the hollow core is formed
from a thermoset shell layer and at least two outer core layers,
wherein an outer core layer is formed from a thermoset material,
and an intermediate core layer, disposed between the shell layer
and the outer core layer, is formed from a thermoplastic material.
In an alternative embodiment, the hollow core includes a thermoset
shell layer and at least two outer core layers, wherein an outer
core layer is formed from a thermoset material, and an intermediate
core layer, disposed between the shell layer and the outer core
layer, is formed from a thermoset material.
[0136] The hollow core may alternatively be formed of a
thermoplastic shell layer that borders and defines the shape of the
innermost aspherical hollow portion. In another embodiment, the
hollow core includes the thermoplastic shell layer and at least two
outer core layers, wherein an outer core layer is formed from a
thermoplastic material, and an intermediate core layer, disposed
between the shell layer and the outer core layer, is formed from a
thermoset material. In an alternative embodiment, the hollow core
includes the thermoplastic shell layer and at least two outer core
layers, wherein an outer core layer is formed from a thermoplastic
material, and an intermediate core layer, disposed between the
shell layer and the outer core layer, is formed from a
thermoplastic material.
[0137] The shell, outer core, or intermediate core layers may have
either a conventional "hard-to-soft" hardness gradient (i.e., the
outermost surface/portion of the layer is harder than the innermost
surface/portion), known as a "positive hardness gradient," or a
"soft-to-hard" hardness gradient (i.e., a "negative" hardness
gradient) as measured radially-inward from the outer surface or
portion of each component towards the innermost portion (i.e., from
the outer surface/portion towards the inner surface/portion of the
shell and/or core layers). As used herein, the terms "negative" and
"positive," with respect to hardness gradient, refer to the result
of subtracting the hardness value at the innermost portion of the
component being measured (e.g., the inner surface of a core layer)
from the hardness value at the outer surface of the component being
measured (e.g., the outer surface of an outer core layer). For
example, if the outer surface of a core layer has a lower hardness
value than at the inner surface, the hardness gradient will be
deemed a "negative" gradient (a smaller number-a larger number=a
negative number), although the magnitude may be disclosed in the
application as the absolute value of the subtraction result in
combination with the designation `negative`).
[0138] The thermoplastic shell, intermediate core layers, and outer
core layers of the invention may have `positive hardness gradients`
or `negative hardness gradients`, as described above.
Alternatively, the thermoplastic layers may have a `zero hardness
gradient`, defined herein to include a 0 Shore C hardness
gradient.+-.2 Shore C. The thermoplastic layer `positive hardness
gradient` or `negative hardness gradient` may be from about 0 Shore
C to about 10 Shore C, or about 2 Shore C to about 8 Shore C, or
about 3 Shore C to about 5 Shore C.
[0139] The thermoset shell, intermediate core layers, and outer
core layers of the invention may have `positive hardness gradients`
or `negative hardness gradients`, as described above.
Alternatively, the thermoset layers may have a `zero hardness
gradient`, defined herein to include a 0 Shore C hardness
gradient.+-.2 Shore C. The thermoset layer `positive hardness
gradient` or `negative hardness gradient` may be from about 1 Shore
C to about 30 Shore C, or about 2 Shore C to about 27 Shore C, or
about 5 Shore C to about 25 Shore C, or about 10 to 20 Shore C.
Other suitable thermoset `positive hardness gradient` or `negative
hardness gradient` core layers can be found in U.S. Pat. Nos.
7,537,529 and 7,537,530, the disclosures of which are incorporated
herein, in their entirety, by reference thereto.
[0140] A variety of the above thermoset and thermoplastic hardness
gradient layers are envisioned and both `positive hardness
gradients` and/or `negative hardness gradients` may be combined to
form the hollow cores of the invention having various layers of
this nature.
[0141] The surface hardness of the shell or core layers is obtained
from the average of a number of measurements taken from opposing
hemispheres of the particular layer, taking care to avoid making
measurements on the parting line or any surface defects, such as
holes or protrusions. Hardness measurements are made pursuant to
ASTM D-2240 "Indentation Hardness of Rubber and Plastic by Means of
a Durometer." Because of the curved surface of the hollow core or
core layers, care must be taken to insure that they are centered
under the durometer indentor before a surface hardness reading is
obtained. A calibrated, digital durometer, capable of reading to
0.1 hardness units is used for all hardness measurements and is set
to take hardness readings 1 second after the maximum reading is
obtained. The digital durometer must be attached to, and its foot
made parallel to, the base of an automatic stand, such that the
weight on the durometer and attack rate conform to ASTM D-2240.
[0142] To prepare the hollow core for hardness and hardness
gradient measurements, the core (shell layer or with one or two
core layers) is gently pressed into a hemispherical holder having
an internal diameter approximately slightly smaller than the
diameter of the core, such that the core is held in place in the
hemispherical portion of the holder while concurrently leaving the
geometric central plane of the core exposed. The core is secured in
the holder by friction, such that it will not move during the
cutting and grinding steps, but the friction is not so excessive
that distortion of the natural shape of the core would result. The
core is secured such that the parting line of the core is roughly
parallel to the top of the holder. The diameter of the core is
measured 90.degree. to this orientation prior to securing. A
measurement is also made from the bottom of the holder to the top
of the core to provide a reference point for future calculations. A
rough cut, made slightly above the exposed geometric center of the
core using a band saw or other appropriate cutting tool, making
sure that the core does not move in the holder during this step.
The remainder of the core, still in the holder, is secured to the
base plate of a surface grinding machine. The exposed `rough` core
surface is ground to a smooth, flat surface, revealing the hollow
portion of the core, which can be verified by measuring the height
of the bottom of the holder to the exposed surface of the core,
making sure that exactly half of the original height of the core,
as measured above, has been removed to within .+-.0.004 inches.
[0143] Leaving the core in the holder, the center of the core is
found with a center square and carefully marked and the hardness is
measured at the center mark. Hardness measurements at any distance
from the center of the core may be measured by drawing a line
radially outward from the center mark, and measuring and marking
the distance from the center, typically in 1- or 2-mm increments.
All hardness measurements performed on the plane passing through
the hollow portion are performed while the core is still in the
holder and without having disturbed its orientation, such that the
test surface is constantly parallel to the bottom of the holder.
The hardness difference from any predetermined location on the core
is calculated as the average surface hardness minus the hardness at
the appropriate reference point.
[0144] One or more of the shell layer and/or core layers may be
formed from a composition including at least one thermoset base
rubber, such as a polybutadiene rubber, cured with at least one
peroxide and at least one reactive co-agent, which can be a metal
salt of an unsaturated carboxylic acid, such as acrylic acid or
methacrylic acid, a non-metallic coagent, or mixtures thereof.
Preferably, a suitable antioxidant is included in the composition.
An optional `soft and fast agent` (sometimes called a cis-to-trans
catalyst), such as an organosulfur or metal-containing organosulfur
or thiol compound, can also be included in the core formulation.
Other ingredients that are known to those skilled in the art may be
used, and are understood to include, but not be limited to,
density-adjusting fillers, process aides, plasticizers, blowing or
foaming agents, sulfur accelerators, and/or non-peroxide radical
sources.
[0145] The base thermoset rubber, which can be blended with other
rubbers and polymers, typically includes a natural or synthetic
rubber. For example, the base rubber can be 1,4-polybutadiene
having a cis structure of at least 40%, preferably greater than
80%, and more preferably greater than 90%.
[0146] Examples of desirable polybutadiene rubbers include
BUNA.RTM. CB22 and BUNA.RTM. CB23, CB1221, CB1220, CB24, and CB21,
commercially-available from LANXESS Corporation; UBEPOL.RTM. 360L
and UBEPOL.RTM. 150L and UBEPOL-BR rubbers, commercially available
from UBE Industries, Ltd. of Tokyo, Japan; KINEX.RTM. 7245,
KINEX.RTM. 7265, and BUDENE 1207 and 1208, commercially available
from Goodyear of Akron, Ohio; SE BR-1220; Europrene.RTM.
NEOCIS.RTM. BR 40 and BR 60, commercially available from Polimeri
Europa; and BR 01, BR 730, BR 735, BR 11, and BR 51, commercially
available from Japan Synthetic Rubber Co., Ltd; PETROFLEX.RTM.
BRNd-40; and KARBOCHEM.RTM. ND40, ND45, and ND60, commercially
available from Karbochem.
[0147] From the Lanxess Corporation, are for example the Nd- and
Co-catalyzed grades, but all of the following may be used: BUNA CB
21; BUNA CB 22; BUNA CB 23; BUNA CB 24; BUNA CB 25; BUNA CB 29 MES;
BUNA CB Nd 40; BUNA CB Nd 40 H; BUNA CB Nd 60; BUNA CB 55 NF; BUNA
CB 60; BUNA CB 45 B; BUNA CB 55 B; BUNA CB 55 H; BUNA CB 55 L; BUNA
CB 70 B; BUNA CB 1220; BUNA CB 1221; BUNA CB 1203; BUNA CB 45.
Additionally, numerous suitable rubbers are available from JSR
(Japan Synthetic Rubber), UBEPOL sold by Ube Industries Inc, Japan,
BST sold by BST Elastomers, Thailand; IPCL sold by Indian
Petrochemicals Ltd, India; NITSU sold by Karbochem or Karbochem Ltd
of South Africa; PETROFLEX of Brazil; LG of Korea; and Kuhmo
Petrochemical of Korea.
[0148] The base rubber may also comprise high or medium Mooney
viscosity rubber, or blends thereof. A "Mooney" unit is a unit used
to measure the plasticity of raw or unvulcanized rubber and is
defined according to ASTM D-1646. The Mooney viscosity range may
for example be greater than about 40, or in the range of from about
40 to 60, or in the range from about 40 to 52.
[0149] Commercial sources of suitable polybutadienes include Bayer
AG CB23 (Nd-catalyzed), which has a Mooney viscosity of around 50
and is a highly linear polybutadiene, and CB1221 (Co-catalyzed). If
desired, the polybutadiene can also be mixed with other elastomers
known in the art, such as other polybutadiene rubbers, natural
rubber, styrene butadiene rubber, and/or isoprene rubber in order
to further modify the properties of the core. When a mixture of
elastomers is used, the amounts of other constituents in the core
composition are typically based on 100 parts by weight of the total
elastomer mixture.
[0150] In one embodiment, the base rubber comprises a Nd-catalyzed
polybutadiene, a rare earth-catalyzed polybutadiene rubber, or
blends thereof. If desired, the polybutadiene can also be mixed
with other elastomers known in the art such as natural rubber,
polyisoprene rubber and/or styrene-butadiene rubber in order to
modify the properties of the core. Other suitable base rubbers
include thermosetting materials such as, ethylene propylene diene
monomer rubber, ethylene propylene rubber, butyl rubber, halobutyl
rubber, hydrogenated nitrile butadiene rubber, nitrile rubber, and
silicone rubber.
[0151] Suitable peroxide initiating agents include dicumyl
peroxide; 2,5-dimethyl-2,5-di(t-butylperoxy)hexane;
2,5-dimethyl-2,5-di(t-butylperoxy)hexyne;
2,5-dimethyl-2,5-di(benzoylperoxy)hexane;
2,2'-bis(t-butylperoxy)-di-iso-propylbenzene;
1,1-bis(t-butylperoxy)-3,3,5-trimethyl cyclohexane; n-butyl
4,4-bis(t-butyl-peroxy)valerate; t-butyl perbenzoate; benzoyl
peroxide; n-butyl 4,4'-bis(butylperoxy)valerate; di-t-butyl
peroxide; or 2,5-di-(t-butylperoxy)-2,5-dimethyl hexane, lauryl
peroxide, t-butyl hydroperoxide, .alpha.-.alpha.
bis(t-butylperoxy)diisopropylbenzene,
di(2-t-butyl-peroxyisopropyl)benzene, di-t-amyl peroxide,
di-t-butyl peroxide. For example, the rubber composition may
include from about 0.25 to about 5.0 parts by weight peroxide per
100 parts by weight rubber (phr), or 0.5 phr to 3 phr, or 0.5 phr
to 1.5 phr. In one embodiment, the peroxide is present in an amount
of about 0.8 phr. These ranges of peroxide are given assuming the
peroxide is 100% active, without accounting for any carrier that
might be present. Because many commercially available peroxides are
sold along with a carrier compound, the actual amount of active
peroxide present must be calculated. Commercially-available
peroxide initiating agents include DICUP.TM. family of dicumyl
peroxides (including DICUP.TM. R, DICUP.TM. 40C and DICUP.TM. 40KE)
available from Crompton (Geo Specialty Chemicals). Similar
initiating agents are available from AkroChem, Lanxess,
Flexsys/Harwick and R. T. Vanderbilt. Another
commercially-available initiating agent is TRIGONOX.TM. 265-50B
from Akzo Nobel, which is a mixture of
1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane and
di(2-t-butylperoxyisopropyl)benzene. TRIGONOX.TM. peroxides are
generally sold on a carrier compound.
[0152] Suitable reactive co-agents include, but are not limited to,
metal salts of diacrylates, dimethacrylates, and monomethacrylates
suitable for use in this invention include those wherein the metal
is zinc, magnesium, calcium, barium, tin, aluminum, lithium,
sodium, potassium, iron, zirconium, and bismuth. Zinc diacrylate
(ZDA) is preferred, but the present invention is not limited
thereto. ZDA provides golf balls with a high initial velocity. The
ZDA can be of various grades of purity. For the purposes of this
invention, the lower the quantity of zinc stearate present in the
ZDA the higher the ZDA purity. ZDA containing less than about 10%
zinc stearate is preferable. More preferable is ZDA containing
about 4-8% zinc stearate. Suitable, commercially available zinc
diacrylates include those from Sartomer Co. Examples of
concentrations of ZDA that can be used are about 10 phr to about 40
phr, or 20 phr to about 35 phr, or 25 phr to about 35 phr. In one
embodiment, the reactive co-agent is present in an amount of about
29 phr to about 31 phr.
[0153] Additional co-agents that may be used alone or in
combination with those mentioned above include, but are not limited
to, trimethylolpropane trimethacrylate, trimethylolpropane
triacrylate, and the like. It is understood by those skilled in the
art, that in the case where these co-agents may be liquids at room
temperature, it may be advantageous to disperse these compounds on
a suitable carrier to promote ease of incorporation in the rubber
mixture.
[0154] Antioxidants are compounds that inhibit or prevent the
oxidative breakdown of elastomers, and/or inhibit or prevent
reactions that are promoted by oxygen radicals. Some exemplary
antioxidants that may be used in the present invention include, but
are not limited to, quinoline type antioxidants, amine type
antioxidants, and phenolic type antioxidants. A preferred
antioxidant is 2,2'-methylene-bis-(4-methyl-6-t-butylphenol)
available as VANOX.RTM. MBPC from R. T. Vanderbilt. Other
polyphenolic antioxidants include VANOX.RTM. T, VANOX.RTM. L,
VANOX.RTM. SKT, VANOX.RTM. SWP, VANOX.RTM. 13 and VANOX.RTM.
1290.
[0155] Suitable antioxidants include, but are not limited to,
alkylene-bis-alkyl substituted cresols; substituted phenols;
alkylene bisphenols; and alkylene trisphenols. The antioxidant is
typically present in an amount of about 0.1 phr to 5 phr, or from
about 0.1 phr to 2 phr, or about 0.1 phr to 1 phr. In an
alternative embodiment, the antioxidant should be present in an
amount to ensure that the hardness gradient of the core layers is
"negative." For example, about 0.2 phr to 1 phr antioxidant may be
added to the core layer formulation, or about 0.3 to 0.8 phr, or
0.4 to 0.7 phr. About 0.25 phr to 1.5 phr of peroxide as calculated
at 100% active can be added to the core formulation, or about 0.5
phr to 1.2 phr, or about 0.7 phr to 1.0 phr. The ZDA amount can be
varied to suit the desired compression, spin and feel of the
resulting golf ball. The cure regime can have a temperature range
from about 290.degree. F. to 350.degree. F., or about 300.degree.
F. to 335.degree. F., and the stock is held at that temperature for
about 10 minutes to 30 minutes fore example.
[0156] The thermoset rubber compositions may also include an
optional `soft and fast agent`. As used herein, "soft and fast
agent" means any compound or a blend thereof that that is capable
of making a core 1) be softer (lower compression) at constant COR
or 2) have a higher COR at equal compression, or any combination
thereof, when compared to a core equivalently prepared without a
soft and fast agent. The thermoset core layer compositions may for
example contain about 0.05 phr to 10.0 phr soft and fast agent. In
one embodiment, the soft and fast agent is present in an amount of
about 0.05 phr to 3.0 phr, or about 0.05 phr to 2.0 phr, or about
0.05 phr to 1.0 phr. In another embodiment, the soft and fast agent
is present in an amount of about 2.0 phr to 5.0 phr, or about 2.35
phr to 4.0 phr, or about 2.35 phr to 3.0 phr. Suitable soft and
fast agents include, but are not limited to, organosulfur or
metal-containing organosulfur compounds, an organic sulfur
compound, including mono, di, and polysulfides, a thiol, or
mercapto compound, an inorganic sulfide compound, a Group VIA
compound, or mixtures thereof. The soft and fast agent component
may also be a blend of an organosulfur compound and an inorganic
sulfide compound.
[0157] Fillers may be added to the thermoset rubber layer
compositions typically include, but are not limited to, processing
aids and/or compounds to affect rheological and mixing properties,
density-modifying fillers, tear strength, or reinforcement fillers,
and the like. Fillers include materials such as tungsten, zinc
oxide, barium sulfate, silica, calcium carbonate, zinc carbonate,
metals, metal oxides and salts, regrind (recycled core material
typically ground to about 30 mesh particle size),
high-Mooney-viscosity rubber regrind, trans-rubber regrind
(recycled core material containing high trans isomer of
polybutadiene), and the like. When trans-regrind is present, the
amount of trans isomer can preferably be between about 10% and 60%.
The fillers are generally inorganic and suitable fillers include
numerous metals or metal oxides, such as zinc oxide and tin oxide,
as well as barium sulfate, zinc sulfate, calcium carbonate, barium
carbonate, clay, tungsten, tungsten carbide, an array of silicas,
and mixtures thereof. Fillers may also include various foaming
agents or blowing agents which may be readily selected by one of
ordinary skill in the art. Fillers may include polymeric, ceramic,
metal, and glass microspheres may be solid or hollow, and filled or
unfilled. Fillers may be added to one or more layers of the golf
ball to modify the density thereof.
[0158] The thermoset rubber shell and/or core layers may optionally
include at least one additive and/or filler. These materials are
also suitable for inclusion in the thermoplastic layers of the
present invention. Suitable additives and fillers include, but are
not limited to, chemical blowing and foaming agents, optical
brighteners, coloring agents, fluorescent agents, whitening agents,
UV absorbers, light stabilizers, defoaming agents, processing aids,
antioxidants, stabilizers, softening agents, fragrance components,
plasticizers, impact modifiers, TiO.sub.2, acid copolymer wax,
surfactants, performance additives (e.g., A-C performance
additives, particularly A-C low molecular weight ionomers and
copolymers, A-C oxidized polyethylenes, and A-C ethylene vinyl
acetate waxes, commercially available from Honeywell International
Inc.), fatty acid amides (e.g., ethylene bis-stearamide and
ethylene bis-oleamide), fatty acids and salts thereof (e.g.,
stearic acid, oleic acid, zinc stearate, magnesium stearate, zinc
oleate, and magnesium oleate), and fillers, such as zinc oxide, tin
oxide, barium sulfate, zinc sulfate, calcium oxide, calcium
carbonate, zinc carbonate, barium carbonate, tungsten, tungsten
carbide, silica, lead silicate, regrind, clay, mica, talc,
nano-fillers, carbon black, glass flake, milled glass, flock,
fibers, and mixtures thereof. Suitable additives are more fully
described in, U.S. Pat. No. 7,041,721 which issued on May 9, 2006,
the disclosure of which is hereby incorporated herein by reference.
In a particular embodiment, the total amount of additive(s) and
filler(s) present in the particle composition is 20 wt % or less,
or 15 wt % or less, or 12 wt % or less, or 10 wt % or less, or 9 wt
% or less, or 6 wt % or less, or 5 wt % or less, or 4 wt % or less,
or 3 wt % or less, or within a range having a lower limit of 0 or 2
or 3 or 5 wt %, based on the total weight of the particle
composition, and an upper limit of 9 or 10 or 12 or 15 or 20 wt %,
based on the total weight of the particle composition. In a
particular aspect of this embodiment, the particle composition
includes fillers selected from carbon black, micro- and nano-scale
clays and organoclays, including (e.g., CLOISITE and NANOFIL
nanoclays, commercially available from Southern Clay Products,
Inc.; NANOMAX and NANOMER nanoclays, commercially available from
Nanocor, Inc., and PERKALITE nanoclays, commercially available from
Akzo Nobel Polymer Chemicals), micro- and nano-scale talcs (e.g.,
LUZENAC HAR high aspect ratio talcs, commercially available from
Luzenac America, Inc.), glass (e.g., glass flake, milled glass,
microglass, and glass fibers), micro- and nano-scale mica and
mica-based pigments (e.g., IRIODIN pearl luster pigments,
commercially available from The Merck Group), and combinations
thereof. Particularly suitable combinations of fillers include, but
are not limited to, micro-scale fillers combined with nano-scale
fillers, and organic fillers with inorganic fillers.
[0159] Alternatively, the thermoset layers herein may be formed
from a castable, pourable reactive material such as a castable
polyurea or a castable polyurethane; castable hybrid
poly(urethane/urea); and castable hybrid poly(urea/urethane).
Suitable polyurethanes include for example those disclosed in U.S.
Pat. Nos. 5,334,673 and 6,506,851. Suitable polyureas include for
example those disclosed in U.S. Pat. Nos. 5,484,870 and 6,835,794.
These patents are incorporated herein by reference thereto.
[0160] For the thermoset layers of the invention, the fillers
and/or additives are present in an amount of about 50 wt % or less,
or 30 wt % or less, or 20 wt % or less, or 15 wt % or less, based
on the total weight of the composition. Alternatively, for the
thermoplastic layers of the invention, the fillers and/or additives
are present in an amount of about 10 wt % or less, or 6 wt % or
less, or 3 wt % or less, based on the total weight of the
composition.
[0161] The particle composition optionally includes one or more
melt flow modifiers. Suitable melt flow modifiers include materials
which increase the melt flow of the composition, as measured using
ASTM D-1238, condition E, at 190.degree. C., using a 2160-g weight.
Examples of suitable melt flow modifiers include, but are not
limited to, fatty acids and fatty acid salts, including, but not
limited to, those disclosed in U.S. Pat. No. 5,306,760, the
disclosure of which is hereby incorporated herein by reference;
fatty amides and salts thereof; polyhydric alcohols, including, but
not limited to, those disclosed in U.S. Pat. Nos. 7,365,128 and
8,163,823, the entire disclosures of which are hereby incorporated
herein by reference; polylactic acids, including, but not limited
to, those disclosed in U.S. Pat. No. 7,642,319, the disclosure of
which is hereby incorporated herein by reference; and the modifiers
disclosed in U.S. Pat. No. 8,163,823 and U.S. Patent Application
Publication No. 2009/0203469, the disclosures of which are hereby
incorporated herein by reference. Flow enhancing additives also
include, but are not limited to, montanic acids, esters of montanic
acids and salts thereof, bis-stearoylethylenediamine, mono- and
polyalcohol esters such as pentaerythritol tetrastearate,
zwitterionic compounds, and metallocene-catalyzed polyethylene and
polypropylene wax, including maleic anhydride modified versions
thereof, amide waxes and alkylene diamides such as bistearamides.
Particularly suitable fatty amides include, but are not limited to,
saturated fatty acid monoamides (e.g., lauramide, palmitamide,
arachidamide behenamide, stearamide, and 12-hydroxy stearamide);
unsaturated fatty acid monoamides (e.g., oleamide, erucamide, and
ricinoleamide); N-substituted fatty acid amides (e.g., N-stearyl
stearamide, N-behenyl behenamide, N-stearyl behenamide, N-behenyl
stearamide, N-oleyl oleamide, N-oleyl stearamide, N-stearyl
oleamide, N-stearyl erucamide, erucyl erucamide, and erucyl
stearamide, N-oleyl palmitamide, methylol amide (preferably
methylol stearamide, methylol behenamide); saturated fatty acid
bis-amides (e.g., methylene bis-stearamide, ethylene
bis-stearamide, ethylene bis-isostearamide, ethylene
bis-hydroxystearamide, ethylene bis-behenamide, hexamethylene
bis-stearamide, hexamethylene bis-behenamide, hexamethylene
bis-hydroxystearamide, N,N'-distearyl adipamide, and N,N'-distearyl
sebacamide); unsaturated fatty acid bis-amides (e.g., ethylene
bis-oleamide, hexamethylene bis-oleamide, N,N'-dioleyl adipamide,
N,N'-dioleyl sebacamide); and saturated and unsaturated fatty acid
tetra amides, stearyl erucamide, ethylene bis stearamide and
ethylene bis oleamide. Suitable examples of commercially available
fatty amides include, but are not limited to, KEMAMIDE fatty acids,
such as KEMAMIDE B (behenamide/arachidamide), KEMAMIDE W40
(N,N'-ethylenebisstearamide), KEMAMIDE P181 (oleyl palmitamide),
KEMAMIDE S (stearamide), KEMAMIDE U (oleamide), KEMAMIDE E
(erucamide), KEMAMIDE O (oleamide), KEMAMIDE W45
(N,N'-ethylenebisstearamide), KENAMIDE W20
(N,N'-ethylenebisoleamide), KEMAMIDE E180 (stearyl erucamide),
KEMAMIDE E221 (erucyl erucamide), KEMAMIDE S180 (stearyl
stearamide), KEMAMIDE 5221 (erucyl stearamide), commercially
available from Chemtura Corporation; and CRODAMIDE fatty amides,
such as CRODAMIDE OR (oleamide), CRODAMIDE ER (erucamide),
CRODAMIDE SR (stereamide), CRODAMIDE BR (behenamide), CRODAMIDE 203
(oleyl palmitamide), and CRODAMIDE 212 (stearyl erucamide),
commercially available from Croda Universal Ltd.
[0162] The shell layer, and intermediate and outer core layers of
the hollow golf ball may also be formed from thermoplastic
materials such as ionomeric polymers, and highly- and
fully-neutralized ionomers (HNP). Acid moieties of the HNP's,
typically ethylene-based ionomers, can be neutralized greater than
about 80%, or greater than about 90%, or even about 100% or
greater. The HNP's can be also be blended with a second polymer
component, which, if containing an acid group, may be neutralized
in a conventional manner, by the organic fatty acids of the present
invention, or both. The second polymer component, which may be
partially- or fully-neutralized, may comprise ionomeric copolymers
and terpolymers, ionomer precursors, thermoplastics, polyamides,
polycarbonates, polyesters, polyurethanes, polyureas, thermoplastic
elastomers, polybutadiene rubber, balata, metallocene-catalyzed
polymers (grafted and non-grafted), single-site polymers,
high-crystalline acid polymers, cationic ionomers, and the like.
HNP polymers typically have a material hardness of between about 20
and about 80 Shore D, and a flexural modulus of between about 3,000
psi and about 200,000 psi.
[0163] The HNP's may be ionomers and/or their acid precursors that
are neutralized, either fully or partially, with organic acid
copolymers or the salts thereof. The acid copolymers are often
preferably .alpha.-olefin, such as ethylene, C.sub.3-8
.alpha.,.beta.-ethylenically unsaturated carboxylic acid, such as
acrylic and methacrylic acid, copolymers. They may optionally
contain a softening monomer, such as alkyl acrylate and alkyl
methacrylate, wherein the alkyl groups have from 1 to 8 carbon
atoms.
[0164] The acid copolymers can be described as E/X/Y copolymers
where E is ethylene, X is an .alpha.,.beta.-ethylenically
unsaturated carboxylic acid, and Y is a softening comonomer. In a
preferred embodiment, X is acrylic or methacrylic acid and Y is a
C.sub.1-8 alkyl acrylate or methacrylate ester. X is often
preferably present in an amount from about 1 to about 35 weight
percent of the polymer, or from about 5 to about 30 weight percent
of the polymer, or from about 10 to about 20 weight percent of the
polymer. Y is often preferably present in an amount from about 0 to
about 50 weight percent of the polymer, or from about 5 to about 25
weight percent of the polymer, or from about 10 to about 20 weight
percent of the polymer.
[0165] Specific acid-containing ethylene copolymers include, but
are not limited to, ethylene/acrylic acid/n-butyl acrylate,
ethylene/methacrylic acid/n-butyl acrylate, ethylene/methacrylic
acid/iso-butyl acrylate, ethylene/acrylic acid/iso-butyl acrylate,
ethylene/methacrylic acid/n-butyl methacrylate, ethylene/acrylic
acid/methyl methacrylate, ethylene/acrylic acid/methyl acrylate,
ethylene/methacrylic acid/methyl acrylate, ethylene/methacrylic
acid/methyl methacrylate, and ethylene/acrylic acid/n-butyl
methacrylate. Preferred acid-containing ethylene copolymers
include, ethylene/methacrylic acid/n-butyl acrylate,
ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylic
acid/methyl acrylate, ethylene/acrylic acid/ethyl acrylate,
ethylene/methacrylic acid/ethyl acrylate, and ethylene/acrylic
acid/methyl acrylate copolymers. The most preferred acid-containing
ethylene copolymers are, ethylene/(meth)acrylic acid/n-butyl,
acrylate, ethylene/(meth)acrylic acid/ethyl acrylate, and
ethylene/(meth)acrylic acid/methyl acrylate copolymers.
[0166] Ionomers are typically neutralized with a metal cation, such
as Li, Na, Mg, K, Ca, or Zn. It has been found that by adding
sufficient organic acid or salt of organic acid, along with a
suitable base, to the acid copolymer or ionomer, however, the
ionomer can be neutralized, without losing processability, to a
level much greater than for a metal cation. The acid moieties may
be neutralized greater than about 80%, or from 90-100%, or 100% or
greater without losing processability. This accomplished by
melt-blending an ethylene .alpha.,.beta.-ethylenically unsaturated
carboxylic acid copolymer, for example, with an organic acid or a
salt of organic acid, and adding a sufficient amount of a cation
source to increase the level of neutralization of all the acid
moieties (including those in the acid copolymer and in the organic
acid) to greater than 90%, or greater than 100%.
[0167] The organic acids are typically aliphatic, mono- or
multi-functional (saturated, unsaturated, or multi-unsaturated)
organic acids. Salts of these organic acids may also be employed.
The salts of organic acids of the present invention include the
salts of barium, lithium, sodium, zinc, bismuth, chromium, cobalt,
copper, potassium, strontium, titanium, tungsten, magnesium,
cesium, iron, nickel, silver, aluminum, tin, or calcium, salts of
fatty acids, particularly stearic, behenic, erucic, oleic, linoelic
or dimerized derivatives thereof. It is preferred that the organic
acids and salts of the present invention be relatively
non-migratory (they do not bloom to the surface of the polymer
under ambient temperatures) and non-volatile (they do not
volatilize at temperatures required for melt-blending).
[0168] The ionomers of the invention may also be more conventional
ionomers, i.e., partially-neutralized with metal cations. The acid
moiety in the acid copolymer may be neutralized about 1 to about
90%, or at least about 20 to about 75%, or at least about 40 to
about 70%, to form an ionomer, by a cation such as lithium, sodium,
potassium, magnesium, calcium, barium, lead, tin, zinc, aluminum,
or a mixture thereof.
[0169] Examples of thermoplastic materials are disclosed in U.S.
Pat. No. 7,591,742, the disclosure of which is incorporated herein
in its entirety by reference thereto.
[0170] Thermoplastic elastomers (TPE) many also be used for the
thermoplastic shell or core layers and/or to modify the properties
of the shell and/or core layers, or the uncured rubber core layer
stock by blending with the base thermoset rubber. These TPEs
include natural or synthetic balata, or high trans-polyisoprene,
high trans-polybutadiene, or any styrenic block copolymer, such as
styrene ethylene butadiene styrene, styrene-isoprene-styrene, etc.,
a metallocene or other single-site catalyzed polyolefin such as
ethylene-octene, or ethylene-butene, or thermoplastic polyurethanes
(TPU), including copolymers, e.g. with silicone. Other suitable
TPEs for blending with the thermoset rubbers of the present
invention include PEBAX.RTM., which is believed to comprise
polyether amide copolymers, HYTREL.RTM., which is believed to
comprise polyether ester copolymers, thermoplastic urethane, and
KRATON.RTM., which is believed to comprise styrenic block
copolymers elastomers. Any of the TPEs or TPUs above may also
contain functionality suitable for grafting, including maleic acid
or maleic anhydride.
[0171] Additional polymers may also optionally be incorporated into
the base rubber for the shell and core layers. Examples include,
but are not limited to, thermoset elastomers such as core regrind,
thermoplastic vulcanizate, copolymeric ionomer, terpolymeric
ionomer, polycarbonate, polyamide, copolymeric polyamide,
polyesters, polyvinyl alcohols, acrylonitrile-butadiene-styrene
copolymers, polyarylate, polyacrylate, polyphenylene ether,
impact-modified polyphenylene ether, high impact polystyrene,
diallyl phthalate polymer, styrene-acrylonitrile polymer (SAN)
(including olefin-modified SAN and
acrylonitrile-styrene-acrylonitrile polymer), styrene-maleic
anhydride copolymer, styrenic copolymer, functionalized styrenic
copolymer, functionalized styrenic terpolymer, styrenic terpolymer,
cellulose polymer, liquid crystal polymer, ethylene-vinyl acetate
copolymers, polyurea, and polysiloxane or any metallocene-catalyzed
polymers of these species.
[0172] Suitable polyamides for use as an additional polymeric
material in compositions within the scope of the present invention
also include resins obtained by: (1) polycondensation of (a) a
dicarboxylic acid, such as oxalic acid, adipic acid, sebacic acid,
terephthalic acid, isophthalic acid, or 1,4-cyclohexanedicarboxylic
acid, with (b) a diamine, such as ethylenediamine,
tetramethylenediamine, pentamethylenediamine, hexamethylenediamine,
or decamethylenediamine, 1,4-cyclohexanediamine, or
m-xylylenediamine; (2) a ring-opening polymerization of cyclic
lactam, such as .epsilon.-caprolactam or .OMEGA.-laurolactam; (3)
polycondensation of an aminocarboxylic acid, such as 6-aminocaproic
acid, 9-aminononanoic acid, 11-aminoundecanoic acid, or
12-aminododecanoic acid; or (4) copolymerization of a cyclic lactam
with a dicarboxylic acid and a diamine. Specific examples of
suitable polyamides include NYLON 6, NYLON 66, NYLON 610, NYLON 11,
NYLON 12, copolymerized NYLON, NYLON MXD6, and NYLON 46.
[0173] Formation of the shell and outer core layers of the
invention may be accomplished in a variety of ways, such as those
disclosed in U.S. Pat. Nos. 5,480,155; 6,315,683, and 8,262,508,
the disclosures of which are incorporated herein, in their
entirety, by reference thereto.
[0174] In one embodiment, the golf ball of the present invention
includes a hollow core. The hollow core is formed from a shell
layer that borders and defines the shape of the innermost
aspherical hollow portion. The shell layer is formed from a
thermoset rubber composition and has an outer surface and an inner
surface. In this embodiment, a single outer core layer is formed
around the shell layer to create a hollow golf ball core. The outer
core layer is also formed from a thermoset material, which may be
the same rubber composition as the shell layer but may be a
different thermoset rubber composition.
[0175] A single cover layer or multiple cover layers may be formed
over the thermoset/thermoset hollow core. In one single cover layer
embodiment, the cover comprises an ionomer having a hardness of at
least 55 Shore D.
[0176] Alternatively, in another embodiment, a dual cover
construction, an inner cover layer and an outer cover layer are
formed over the core. In one embodiment, the inner cover includes
an ionomeric material and the outer cover layer includes a polyurea
or a polyurethane. The outer cover layer is typically softer than
the inner cover layer, such as where the inner cover has a hardness
of greater than about 60 Shore D and the outer cover layer has a
hardness of less than about 60 Shore D; however, the reverse may be
used.
[0177] In the above embodiment, the plurality of extensions and
innermost aspherical hollow portion, combined, can have a diameter
of about 0.51 to 1.1 inches. The surface hardness of the shell
layer is preferably greater than the hardness of the inner surface
of the shell layer by about 3 to 25 Shore C to define a first
hardness gradient. In another embodiment, the thermoset outer core
layer has a hardness gradient that is different from the hardness
gradient of the thermoset shell layer. Most preferably, the shell
layer has a surface hardness greater than about 55 Shore C.
[0178] The thermoset shell layer has a coefficient of restitution
(COR) less than about 0.750 when measured at an incoming velocity
of 125 ft/s. Preferably, the COR is less than about 0.700, more
preferably about 0.500 to 0.700, and most preferably about 0.600 to
0.700. The overall hollow core (the combination of the thermoset
shell layer and the thermoset outer core layer) has a COR, measured
at an incoming velocity of 125 ft/s, higher than the COR of the
shell layer by greater than about 5%, more preferably about 10 to
50%, and most preferably about 15 to 30%.
[0179] In an alternative embodiment, the hardness gradient of the
thermoset outer core layer has a `zero hardness gradient`. The zero
hardness gradient is typically about 0 Shore C (defined herein as
.+-.2 Shore C). The hardness gradient of the thermoset outer core
layer may also have a `negative hardness gradient`, preferably
about 3 to 25 Shore C, more preferably about 5 to 20 Shore C, and
most preferably about 8 to 15 Shore C. The hardness gradient of the
thermoset outer core layer may also have a `positive hardness
gradient`, preferably about 3 to 25 Shore C, more preferably about
5 to 20 Shore C, and most preferably about 8 to 15 Shore C.
[0180] The golf ball has a first volume and the plurality of
extensions and innermost aspherical hollow portion, combined, has a
second volume. The second volume is about 2% to 30% of the first
volume, or the second volume is about 5% to 25% of the first
volume, or the second volume is about 10% to 20% of the first
volume.
[0181] In another embodiment of the invention, the hollow core
further includes a thermoplastic intermediate core layer disposed
between the thermoset shell layer and the thermoset outer core
layer. In still another embodiment, the hollow core further
includes a thermoset intermediate core layer disposed between the
thermoset shell layer and the thermoset outer core layer. The
intermediate core layer may formed from a thermoset rubber
composition which is the same or different from the thermoset
rubber compositions used to form the thermoset shell layer or the
thermoset outer core layer. In these embodiments, the plurality of
extensions and innermost aspherical hollow portion, combined,
preferably has a diameter of about 0.15 to 1.1 inches, the shell
layer has a surface hardness greater than an inner surface hardness
by about 10 to 25 Shore C to define a hardness gradient, preferably
a `positive hardness gradient`. The thermoset outer core layer
preferably has a hardness gradient that is different from the
hardness gradient of the shell layer or the intermediate layer.
[0182] In another embodiment of the invention, the hollow core
further includes a thermoplastic intermediate core layer disposed
between the thermoplastic shell layer and the thermoplastic outer
core layer. In still another embodiment, the hollow core further
includes a thermoset intermediate core layer disposed between the
thermoplastic shell layer and the thermoplastic outer core layer.
The intermediate core layer is preferably formed from a thermoset
rubber composition. In these embodiments, the plurality of
extensions and innermost aspherical hollow portion, combined,
preferably has a diameter of about 0.15 to 1.1 inches, the
thermoplastic shell layer has a surface hardness greater than an
inner surface hardness by about 1 to 10 Shore C to define a
hardness gradient, preferably a `positive hardness gradient`. The
thermoplastic outer core layer preferably has a hardness gradient
that is different from the hardness gradient of the thermoplastic
shell layer or the intermediate layer.
[0183] The golf ball of the present invention includes a hollow
core which is formed from a shell layer having a plurality of
extensions that border and shape the innermost aspherical hollow
portion. The shell layer is formed from a thermoplastic
composition, preferably a conventional ionomer or a
fully-neutralized ionomer. The shell layer has an outer surface and
an inner surface. A single thermoplastic outer core layer is formed
over the shell layer and preferably includes an ionomeric
composition. The combination of the thermoplastic shell layer and
the thermoplastic outer core layer results in a
thermoplastic/thermoplastic hollow core. Typically, an inner cover
layer and an outer cover layer are formed over the thermoplastic
outer core layer. In one embodiment, the inner cover includes an
ionomeric material and the outer cover includes a polyurea or, more
preferably, a polyurethane. The outer cover is preferably softer
than the inner cover layer.
[0184] The plurality of extensions and innermost aspherical hollow
portion, combined, has a diameter of about 0.15 to 1.1 inches,
preferably about 0.25 to 1.0 inches, more preferably about 0.25 to
0.75 inches, and most preferably about 0.3 to 0.5 inches. The
surface hardness of the thermoplastic shell layer is preferably
greater than the hardness of the inner surface of the shell layer
by about 0 to 5 Shore C to define a hardness gradient. The
thermoplastic outer core layer also has a hardness gradient, which
is the same as or greater than the hardness gradient of the
thermoplastic shell layer. In an alternative embodiment, the
hardness gradient of the thermoplastic outer core layer has a `zero
hardness gradient`. The zero hardness gradient is typically about 0
Shore C (defined herein as .+-.2 Shore C). The hardness gradient of
the thermoplastic outer core layer may also have a `negative
hardness gradient`, preferably about 1 to 10 Shore C, more
preferably about 2 to 8 Shore C, and most preferably about 3 to 5
Shore C. The hardness gradient of the thermoplastic outer core
layer may also have a `positive hardness gradient`, preferably
about 1 to 10 Shore C, more preferably about 2 to 8 Shore C, and
most preferably about 3 to 5 Shore C.
[0185] The golf ball has a first volume and the plurality of
extensions and innermost aspherical hollow portion, combined, has a
second volume. The second volume is about 2% to 30% of the first
volume, more preferably about 5% to 25% of the first volume, and
most preferably about 10% to 20% of the first volume.
[0186] The thermoplastic shell layer has a COR less than about
0.750 when measured at an incoming velocity of 125 ft/s.
Preferably, the COR is less than about 0.700, more preferably about
0.500 to 0.700, and most preferably about 0.600 to 0.700. The
overall hollow core (the combination of the thermoplastic shell
layer and the thermoplastic outer core layer has a COR, measured at
an incoming velocity of 125 ft/s, higher than the COR of the shell
layer by greater than about 5%, more preferably about 10 to 50%,
and most preferably about 15 to 30%.
[0187] In another embodiment of the invention, the hollow core
further includes a thermoplastic intermediate core layer disposed
between the thermoplastic shell layer and the thermoplastic outer
core layer. In still another embodiment, the hollow core further
includes a thermoset intermediate core layer disposed between the
thermoplastic shell layer and the thermoplastic outer core layer.
The intermediate core layer is preferably formed from a thermoset
rubber composition. In these embodiments, the plurality of
extensions and innermost aspherical hollow portion, combined,
preferably has a diameter of about 0.15 to 1.1 inches, the
thermoplastic shell layer has a surface hardness greater than an
inner surface hardness by about 1 to 10 Shore C to define a
hardness gradient, preferably a `positive hardness gradient`. The
thermoplastic outer core layer preferably has a hardness gradient
that is different from the hardness gradient of the thermoplastic
shell layer or the intermediate layer.
[0188] The plurality of extensions and innermost aspherical hollow
portion, combined, has a diameter of about 0.15 to 1.1 inches,
preferably about 0.25 to 1.0 inches, more preferably about 0.25 to
0.75 inches, and most preferably about 0.3 to 0.5 inches. The
surface hardness of the thermoplastic shell layer is preferably
greater than the hardness of the inner surface of the shell layer
by about 1 to 5 Shore C to define a first hardness gradient. The
thermoset outer core layer has a second hardness gradient, which is
greater than the hardness gradient of the thermoplastic shell
layer. In an alternative embodiment, the hardness gradient of the
thermoset outer core layer has a `zero hardness gradient`. The zero
hardness gradient is typically about 0 Shore C (defined herein as
.+-.2 Shore C). The hardness gradient of the thermoset outer core
layer may also have a `negative hardness gradient`, preferably
about 3 to 25 Shore C, more preferably about 5 to 20 Shore C, and
most preferably about 8 to 15 Shore C. The hardness gradient of the
thermoset outer core layer may also have a `positive hardness
gradient`, preferably about 3 to 25 Shore C, more preferably about
5 to 20 Shore C, and most preferably about 8 to 15 Shore C.
[0189] In another embodiment of the invention, the hollow core
further includes a thermoplastic intermediate core layer disposed
between the shell layer and the thermoset outer core layer. The
thermoplastic intermediate core layer may be formed from a
thermoplastic material that is the same or different from the
thermoplastic material of the shell layer. In still another
embodiment, the hollow core further includes a thermoset
intermediate core layer disposed between the thermoplastic shell
layer and the thermoset outer core layer. The intermediate core
layer may formed from a thermoset rubber composition which is the
same or different from the thermoset rubber composition used to
form the thermoset outer core layer. In these embodiments, the
plurality of extensions and innermost aspherical hollow portion,
combined, preferably has a diameter of about 0.15 to 1.1 inches,
the thermoplastic shell layer has a surface hardness greater than
an inner surface hardness by about 1 to 5 Shore C to define a first
hardness gradient, preferably a `positive hardness gradient`, and
the thermoset outer core layer or thermoset intermediate core layer
has a second hardness gradient.
[0190] In another embodiment, the inventive golf ball includes the
hollow core. The hollow core includes a shell layer formed from a
first thermoset rubber composition. The shell layer has an outer
surface, an inner surface, and extensions located on the inner
surface that define and shape the innermost aspherical hollow
portion. In this embodiment, a single thermoplastic outer core
layer is disposed about the shell layer to complete the hollow
core. A single cover or, preferably, an inner cover layer is formed
around the outer core layer. When an inner cover layer is present,
an outer cover layer is formed over the inner cover layer. Most
preferably, the inner cover is formed from an ionomeric material
and the outer cover layer is formed from a polyurethane material,
and the outer cover layer has a hardness that is less than that of
the inner cover layer. Preferably, the inner cover has a hardness
of greater than about 60 Shore D and the outer cover layer has a
hardness of less than about 60 Shore D.
[0191] The plurality of extensions and innermost aspherical hollow
portion, combined, has a diameter of about 0.15 to 1.1 inches,
preferably about 0.25 to 1.0 inches, more preferably about 0.25 to
0.75 inches, and most preferably about 0.3 to 0.5 inches. In this
embodiment, the shell layer has a surface hardness that is greater
than its inner surface hardness by about 3 to 25 Shore C to define
a first hardness gradient.
[0192] The thermoplastic outer core layer has a second hardness
gradient. The shell layer has a surface hardness greater than about
55 Shore C. The shell layer has a coefficient of restitution (COR)
less than about 0.750 when measured at an incoming velocity of 125
ft/s. Preferably, the COR is less than about 0.700, more preferably
about 0.500 to 0.700, and most preferably about 0.600 to 0.700. The
overall core (the combination of the hollow core and any outer core
layers) has a COR, measured at an incoming velocity of 125 ft/s,
higher than the COR of the shell layer by greater than about 5%,
more preferably about 10 to 50%, and most preferably about 15 to
30%.
[0193] In an alternative embodiment, the hardness gradient of the
thermoplastic outer core layer has a `zero hardness gradient`. The
zero hardness gradient is typically about 0 Shore C (defined herein
as .+-.2 Shore C). The hardness gradient of the thermoplastic outer
core layer may also have a `negative hardness gradient`, preferably
about 1 to 10 Shore C, more preferably about 2 to 8 Shore C, and
most preferably about 2 to 5 Shore C. The hardness gradient of the
thermoplastic outer core layer may also have a `positive hardness
gradient`, preferably about 1 to 10 Shore C, more preferably about
2 to 8 Shore C, and most preferably about 2 to 5 Shore C.
[0194] The golf ball has a first volume and the plurality of
extensions and innermost aspherical hollow portion, combined, has a
second volume. The second volume is about 2% to 30% of the first
volume, more preferably about 5% to 25% of the first volume, and
most preferably about 10% to 20% of the golf ball volume.
[0195] The hollow core of the present invention (innermost
aspherical hollow portion, shell layer and outer core layer(s)) is
covered by at least one cover layer. An intermediate layer, such as
an inner cover layer, may optionally be disposed about the hollow
core, with the cover layer formed around the intermediate layer as
an outer cover layer. While any of the thermoplastic materials
disclosed herein may be suitable for the inner or outer cover
layers of the invention, in one embodiment the outermost cover is
formed from a castable polyurea or a castable polyurethane;
castable hybrid poly(urethane/urea); and castable hybrid
poly(urea/urethane). Suitable polyurethanes include those disclosed
in U.S. Pat. Nos. 5,334,673 and 6,506,851. Suitable polyureas
include those disclosed in U.S. Pat. Nos. 5,484,870 and 6,835,794.
These patents are incorporated herein by reference thereto.
[0196] Other suitable polyurethane compositions comprise a reaction
product of at least one polyisocyanate and at least one curing
agent. The curing agent can include, for example, one or more
polyamines, one or more polyols, or a combination thereof. The
polyisocyanate can be combined with one or more polyols to form a
prepolymer, which is then combined with the at least one curing
agent. Thus, the polyols described herein are suitable for use in
one or both components of the polyurethane material, i.e., as part
of a prepolymer and in the curing agent. More suitable
polyurethanes are described in U.S. Pat. No. 7,331,878, which is
incorporated by reference in its entirety.
[0197] Any polyisocyanate available to one of ordinary skill in the
art is suitable for use according to the invention. Exemplary
polyisocyanates include, but are not limited to,
4,4'-diphenylmethane diisocyanate (MDI); polymeric MDI;
carbodiimide-modified liquid MDI; 4,4'-dicyclohexylmethane
diisocyanate (H.sub.12MDI); p-phenylene diisocyanate (PPDI);
m-phenylene diisocyanate (MPDI); toluene diisocyanate (TDI);
3,3'-dimethyl-4,4'-biphenylene diisocyanate;
isophoronediisocyanate; 1,6-hexamethylene diisocyanate (HDI);
naphthalene diisocyanate; xylene diisocyanate; p-tetramethylxylene
diisocyanate; m-tetramethylxylene diisocyanate; ethylene
diisocyanate; propylene-1,2-diisocyanate;
tetramethylene-1,4-diisocyanate; cyclohexyl diisocyanate;
dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;
cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate;
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; methyl
cyclohexylene diisocyanate; triisocyanate of HDI; triisocyanate of
2,4,4-trimethyl-1,6-hexane diisocyanate; tetracene diisocyanate;
napthalene diisocyanate; anthracene diisocyanate; isocyanurate of
toluene diisocyanate; uretdione of hexamethylene diisocyanate; and
mixtures thereof. Polyisocyanates are known to those of ordinary
skill in the art as having more than one isocyanate group, e.g.,
di-isocyanate, triisocyanate, and tetra-isocyanate. Preferably, the
polyisocyanate includes MDI, PPDI, TDI, or a mixture thereof, and
more preferably, the polyisocyanate includes MDI. It should be
understood that, as used herein, the term MDI includes
4,4'-diphenylmethane diisocyanate, polymeric MDI,
carbodiimide-modified liquid MDI, and mixtures thereof and,
additionally, that the diisocyanate employed may be "low free
monomer," understood by one of ordinary skill in the art to have
lower levels of "free" monomer isocyanate groups, typically less
than about 0.1% free monomer isocyanate groups. Examples of "low
free monomer" diisocyanates include, but are not limited to Low
Free Monomer MDI, Low Free Monomer TDI, and Low Free Monomer PPDI.
The at least one polyisocyanate should have less than about 14%
unreacted NCO groups. Preferably, the at least one polyisocyanate
has no greater than about 8.0% NCO, more preferably no greater than
about 7.8%, and most preferably no greater than about 7.5% NCO with
a level of NCO of about 7.2 or 7.0, or 6.5% NCO commonly used.
[0198] Any polyol available to one of ordinary skill in the art is
suitable for use according to the invention. Exemplary polyols
include, but are not limited to, polyether polyols,
hydroxy-terminated polybutadiene (including partially/fully
hydrogenated derivatives), polyester polyols, polycaprolactone
polyols, and polycarbonate polyols. In one embodiment, the polyol
includes polyether polyol. Examples include, but are not limited
to, polytetramethylene ether glycol (PTMEG), polyethylene propylene
glycol, polyoxypropylene glycol, and mixtures thereof. The
hydrocarbon chain can have saturated or unsaturated bonds and
substituted or unsubstituted aromatic and cyclic groups.
Preferably, the polyol of the present invention includes PTMEG.
[0199] In another embodiment, polyester polyols are included in the
polyurethane material. Suitable polyester polyols include, but are
not limited to, polyethylene adipate glycol; polybutylene adipate
glycol; polyethylene propylene adipate glycol;
o-phthalate-1,6-hexanediol; poly(hexamethylene adipate)glycol; and
mixtures thereof. The hydrocarbon chain can have saturated or
unsaturated bonds, or substituted or unsubstituted aromatic and
cyclic groups.
[0200] In another embodiment, polycaprolactone polyols are included
in the materials of the invention. Suitable polycaprolactone
polyols include, but are not limited to, 1,6-hexanediol-initiated
polycaprolactone, diethylene glycol initiated polycaprolactone,
trimethylol propane initiated polycaprolactone, neopentyl glycol
initiated polycaprolactone, 1,4-butanediol-initiated
polycaprolactone, and mixtures thereof. The hydrocarbon chain can
have saturated or unsaturated bonds, or substituted or
unsubstituted aromatic and cyclic groups.
[0201] In yet another embodiment, polycarbonate polyols are
included in the polyurethane material of the invention. Suitable
polycarbonates include, but are not limited to, polyphthalate
carbonate and poly(hexamethylene carbonate)glycol. The hydrocarbon
chain can have saturated or unsaturated bonds, or substituted or
unsubstituted aromatic and cyclic groups. In one embodiment, the
molecular weight of the polyol is from about 200 to about 4000.
[0202] Polyamine curatives are also suitable for use in the
polyurethane composition of the invention and have been found to
improve cut, shear, and impact resistance of the resultant balls.
Preferred polyamine curatives include, but are not limited to,
3,5-dimethylthio-2,4-toluenediamine and isomers thereof;
3,5-diethyltoluene-2,4-diamine and isomers thereof, such as
3,5-diethyltoluene-2,6-diamine;
4,4'-bis-(sec-butylamino)-diphenylmethane;
1,4-bis-(sec-butylamino)-benzene,
4,4'-methylene-bis-(2-chloroaniline);
4,4'-methylene-bis-(3-chloro-2,6-diethylaniline);
polytetramethyleneoxide-di-p-aminobenzoate; N,N'-dialkyldiamino
diphenyl methane; p,p'-methylene dianiline; m-phenylenediamine;
4,4'-methylene-bis-(2-chloroaniline);
4,4'-methylene-bis-(2,6-diethylaniline);
4,4'-methylene-bis-(2,3-dichloroaniline);
4,4'-diamino-3,3'-diethyl-5,5'-dimethyl diphenylmethane;
2,2',3,3'-tetrachloro diamino diphenylmethane; trimethylene glycol
di-p-aminobenzoate; and mixtures thereof. Preferably, the curing
agent of the present invention includes
3,5-dimethylthio-2,4-toluenediamine and isomers thereof, such as
ETHACURE.RTM. 300, commercially available from Albermarle
Corporation of Baton Rouge, La. Suitable polyamine curatives, which
include both primary and secondary amines, preferably have
molecular weights ranging from about 64 to about 2000.
[0203] At least one of a diol, triol, tetraol, or
hydroxy-terminated curatives may be added to the aforementioned
polyurethane composition. Suitable diol, triol, and tetraol groups
include ethylene glycol; diethylene glycol; polyethylene glycol;
propylene glycol; polypropylene glycol; lower molecular weight
polytetramethylene ether glycol; 1,3-bis(2-hydroxyethoxy)benzene;
1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene;
1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene;
1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol;
resorcinol-di-(.beta.-hydroxyethyl) ether;
hydroquinone-di-(.beta.-hydroxyethyl) ether; and mixtures thereof.
Preferred hydroxy-terminated curatives include
1,3-bis(2-hydroxyethoxy)benzene;
1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene;
1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene;
1,4-butanediol, and mixtures thereof. Preferably, the
hydroxy-terminated curatives have molecular weights ranging from
about 48 to 2000. It should be understood that molecular weight, as
used herein, is the absolute weight average molecular weight and
would be understood as such by one of ordinary skill in the
art.
[0204] Both the hydroxy-terminated and amine curatives can include
one or more saturated, unsaturated, aromatic, and cyclic groups.
Additionally, the hydroxy-terminated and amine curatives can
include one or more halogen groups. The polyurethane composition
can be formed with a blend or mixture of curing agents. If desired,
however, the polyurethane composition may be formed with a single
curing agent.
[0205] In one embodiment of the present invention, saturated
polyurethanes are used to form one or more of the cover layers,
preferably the outer cover layer, and may be selected from both
castable thermoset and thermoplastic polyurethanes. In this
embodiment, the saturated polyurethanes of the present invention
are substantially free of aromatic groups or moieties. Saturated
polyurethanes suitable for use in the invention are a product of a
reaction between at least one polyurethane prepolymer and at least
one saturated curing agent. The polyurethane prepolymer is a
product formed by a reaction between at least one saturated polyol
and at least one saturated diisocyanate. As is well known in the
art, that a catalyst may be employed to promote the reaction
between the curing agent and the isocyanate and polyol, or the
curing agent and the prepolymer.
[0206] Additionally, polyurethane can be replaced with or blended
with a polyurea material. Polyureas are distinctly different from
polyurethane compositions. The polyurea-based compositions are
preferably saturated in nature. The polyurea compositions may be
formed from the reaction product of an isocyanate and polyamine
prepolymer crosslinked with a curing agent. For example,
polyurea-based compositions of the invention may be prepared from
at least one isocyanate, at least one polyether amine, and at least
one diol curing agent or at least one diamine curing agent.
[0207] Golf balls of the invention and any thermoplastic or
thermoset layer disclosed herein may be formed using a variety of
application techniques such as compression molding, flip molding,
injection molding, retractable pin injection molding, reaction
injection molding (RIM), liquid injection molding (LIM), casting,
vacuum forming, powder coating, flow coating, spin coating,
dipping, spraying, and the like. Conventionally, compression
molding and injection molding are applied to thermoplastic
materials, whereas RIM, liquid injection molding, and casting are
employed on thermoset materials. These and other manufacture
methods are disclosed in U.S. Pat. Nos. 6,207,784 and 5,484,870,
the disclosures of which are incorporated herein by reference in
their entirety.
[0208] For example, intermediate or cover layers may be formed
using any suitable method known to those of ordinary skill in the
art such as by blow molding an intermediate layer and covering with
a dimpled cover layer formed by injection molding, compression
molding, casting, vacuum forming, powder coating, and the like. A
composition may be dry-blended and fed into an injection molding
machine to produce half cups, or may be formed by melt blending and
extruding the components with polymer mixing equipment, such as a
single or twin-screw extruder. Pellets may be dry blended with
other components and then injection molded onto any inner layer.
Compression molding or retractable pin injection molding may be
used to seal cups together and form a finished golf ball.
[0209] A method of injection molding using a split vent pin can be
found in co-pending U.S. Pat. No. 6,877,974, filed Dec. 22, 2000,
entitled "Split Vent Pin for Injection Molding." Examples of
retractable pin injection molding may be found in U.S. Pat. Nos.
6,129,881; 6,235,230; and 6,379,138. These molding references are
incorporated in their entirety by reference herein. In addition, a
chilled chamber, i.e., a cooling jacket, such as the one disclosed
in U.S. Pat. No. 6,936,205, filed Nov. 22, 2000, entitled "Method
of Making Golf Balls" may be used to cool the compositions of the
invention when casting, which also allows for a higher loading of
catalyst into the system.
[0210] Conventionally, compression molding and injection molding
are applied to thermoplastic materials, whereas RIM, liquid
injection molding, and casting are employed on thermoset materials.
These and other manufacture methods are disclosed in U.S. Pat. Nos.
6,207,784 and 5,484,870, the disclosures of which are incorporated
herein by reference in their entirety.
[0211] Castable reactive liquid polyurethanes and polyurea
materials may be applied over the inner ball using a variety of
application techniques such as casting, injection molding spraying,
compression molding, dipping, spin coating, or flow coating methods
that are well known in the art. In one embodiment, the castable
reactive polyurethanes and polyurea material is formed over the
core using a combination of casting and compression molding.
Conventionally, compression molding and injection molding are
applied to thermoplastic cover materials, whereas RIM, liquid
injection molding, and casting are employed on thermoset cover
materials.
[0212] U.S. Pat. No. 5,733,428, the entire disclosure of which is
hereby incorporated by reference, discloses a method for forming a
polyurethane cover on a golf ball core. Because this method relates
to the use of both casting thermosetting and thermoplastic material
as the golf ball cover, wherein the cover is formed around the core
by mixing and introducing the material in mold halves, the polyurea
compositions may also be used employing the same casting
process.
[0213] For example, once a polyurea composition is mixed, an
exothermic reaction commences and continues until the material is
solidified around the core. It is important that the viscosity be
measured over time, so that the subsequent steps of filling each
mold half, introducing the core into one half and closing the mold
can be properly timed for accomplishing centering of the core cover
halves fusion and achieving overall uniformity. A suitable
viscosity range of the curing urea mix for introducing cores into
the mold halves is determined to be approximately between about
2,000 cP and about 30,000 cP, or within a range of about 8,000 cP
to about 15,000 cP.
[0214] To start the cover formation, mixing of the prepolymer and
curative is accomplished in a motorized mixer inside a mixing head
by feeding through lines metered amounts of curative and
prepolymer. Top preheated mold halves are filled and placed in
fixture units using centering pins moving into apertures in each
mold. At a later time, the cavity of a bottom mold half, or the
cavities of a series of bottom mold halves, is filled with similar
mixture amounts as used for the top mold halves. After the reacting
materials have resided in top mold halves for about 40 to about 100
seconds, preferably for about 70 to about 80 seconds, a core is
lowered at a controlled speed into the gelling reacting
mixture.
[0215] A ball cup holds the shell through reduced pressure (or
partial vacuum). Upon location of the core in the halves of the
mold after gelling for about 4 to about 12 seconds, the vacuum is
released allowing the core to be released. In one embodiment, the
vacuum is released allowing the core to be released after about 5
seconds to 10 seconds. The mold halves, with core and solidified
cover half thereon, are removed from the centering fixture unit,
inverted and mated with second mold halves which, at an appropriate
time earlier, have had a selected quantity of reacting polyurea
prepolymer and curing agent introduced therein to commence
gelling.
[0216] Similarly, U.S. Pat. No. 5,006,297 and U.S. Pat. No.
5,334,673 both also disclose suitable molding techniques that may
be utilized to apply the castable reactive liquids employed in the
present invention.
[0217] However, golf balls of the invention may be made by any
known technique to those skilled in the art.
[0218] While any of the embodiments herein may have any known
dimple number and pattern, a the number of dimples may be 252 to
456, or 330 to 392, for example. The dimples may comprise any
width, depth, and edge angle disclosed in the prior art and the
patterns may comprises multitudes of dimples having different
widths, depths and edge angles. The parting line configuration of
said pattern may be either a straight line or a staggered wave
parting line (SWPL). Most preferably the dimple number is 330, 332,
or 392 and comprises 5 to 7 dimples sizes and the parting line is a
SWPL.
[0219] In any of these embodiments the single-layer core may be
replaced with a 2 or more layer core wherein at least one core
layer has a negative hardness gradient. Other than in the operating
examples, or unless otherwise expressly specified, all of the
numerical ranges, amounts, values and percentages such as those for
amounts of materials and others in the specification may be read as
if prefaced by the word "about" even though the term "about" may
not expressly appear with the value, amount or range. Accordingly,
unless indicated to the contrary, the numerical parameters set
forth in the specification and attached claims are approximations
that may vary depending upon the desired properties sought to be
obtained by the present invention. At the very least, and not as an
attempt to limit the application of the doctrine of equivalents to
the scope of the claims, each numerical parameter should at least
be construed in light of the number of reported significant digits
and by applying ordinary rounding techniques.
[0220] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical value, however,
inherently contain certain errors necessarily resulting from the
standard deviation found in their respective testing measurements.
Furthermore, when numerical ranges of varying scope are set forth
herein, it is contemplated that any combination of these values
inclusive of the recited values may be used.
[0221] While it is apparent that the illustrative embodiments of
the invention disclosed herein fulfill the objective stated above,
it is appreciated that numerous modifications and other embodiments
may be devised by those skilled in the art. Therefore, it will be
understood that the appended claims are intended to cover all such
modifications and embodiments, which would come within the spirit
and scope of the present invention.
* * * * *